To the OP..of course you are going to use your own best judgment..perhaps this will be useful
http://www.saferparks.org/preventing_injuries/child_safety/tips_for_parents.php
Tips for Parents
What Parents Should Know About Ride Safety for Young Children
1. Be a cautious consumer when choosing amusement rides for your child.
Amusement rides are no different than any other kind of product targeted at children. They offer benefits and risks. Use the same good judgment when picking amusement rides that you do when deciding which foods or TV shows or toys are safe for your kids. Just because a ride attendant says it's okay with them if your toddler rides alone on a kiddie train, that doesn't mean he won't fall off and be seriously hurt.
Don't assume that your child will be safe on a ride simply because the ride operator says it's okay,
or the child meets the posted height requirement.
Learn to judge for yourself whether the ride is safe for your child. Be conservative in your judgments.
Understand that amusement rides are not child safe or childproof. There are no mandatory federal safety standards for amusement rides, or regulatory oversight of amusement ride design.
Height guidelines are set by the manufacturers, and do not always take the developmental stages of childhood into account. Click here for more information about height limits.
2. Watch the ride with your child before boarding.
Read warning signs aloud.
Point out the ride attendants and the loading/unloading locations.
Explain that rides sometimes stop temporarily, but that riders must never get off until the attendant tells them to.
Talk about what to do if your child gets frightened while the ride is moving. Tell her NOT to get out of the car. Explain that amusement rides might seem scary, but they're not dangerous as long as riders hold on tight, stay seated, and keep their hands and feet inside.
Tell children to hold on tightly with both hands. Solid metal lap bars and handholds are part of the safety equipment. Teach your children to use them.
Many kids raised in the era of five-point car seat restraint systems don't know that holding on is important.
3. Always obey minimum height, age, weight, and health restrictions.
Never sneak children onto rides they're too small or too young for. Ride manufacturers' restrictions take into account the forces exerted by the ride and (sometimes) the intellectual maturity required to ride safely. A smaller/younger child may not be physically or developmentally able to stay safely seated.
Use the posted height and age limits as suggestions, not pass/fail criteria. Manufacturers base their guidelines on developmental timelines and height/weight ratios of children in the 50th percentile. Kids who are tall for their age may not be developmentally ready for a particular ride. Kids who are more impulsive than average need closer parental supervision.
Don't put your child on a ride he's outgrown. Maximum height and weight limits are just as important as minimum limits.
If you can' t count on your child to stay seated with hands and feet inside, don't let him or her ride.
4. Don't put children on rides they're afraid of.
When a child gets scared, her first impulse is to get away from whatever frightened her. When asked what they should do if they get scared while a ride is moving, a class of 20 preschoolers answered "get off the ride" . Children are hurt every year doing exactly that.
5. Seat small children to the inside, away from open sides.
6. Always use the safety equipment provided, but be aware of its limitations.
Ride manufacturers provide seatbelts, lap bars, and other safety equipment to reduce the risk of injury.
However, many safety devices used on children's amusement rides aren't designed to keep young children in their seats.
Do not rely on lap bars and ropes to restrain children.
They're designed as "psychological barriers", an incentive to stay seated. Unfortunately parents understand psychology better than kids, so Mom sees a "restraint" and her clever child sees "a piece of metal to climb under".
Solid metal lap bars only fit closely against the largest passenger in the car, often leaving young children with room to slide around. If a lap bar doesn't fit closely, a fast-moving ride can cause a child to slip completely out from underneath the bar. Loose-fitting lap bars also allow young children to stand up on their own while a ride is moving.
There are no mandatory federal standards for the design of amusement rides. Amusement rides are neither childproof nor child-safe. Use good judgment when deciding whether your kids should ride. Click here for more information about ride restraints and children.
7. Watch all extremities - including feet if the ride has open sides.
Excited children often stick hands, arms, feet or even their heads out the sides of amusement rides. Load children to the inside, away from open doorways, or on the side closest to the ride operator.
Pay special attention as the ride slows to a stop. Children who are in a rush to be the first one off, or in a hurry to get to the next ride, may try to exit while the ride is still moving.
8. Teach small children what to do if they get separated from you.
Point out uniformed park employees, so they know who's in charge of finding lost parents. Choose an obvious landmark as a meeting place.
9. Don't abdicate your parental responsibility or your judgment to any business.
Parents often feel overly-confident about putting their children on attended amusement rides, especially those operated by successful, well-respected corporations. Don't confuse profitability with protection. Your children need your protection, whether they're in your back yard or
Disneyland.
10. Remember that amusement rides aren't really magic.
Never forget that you're loading very young children onto heavy machinery at amusement parks and exposing them to water hazards at water parks.
Summary
Most kiddie rides are safe for most kids most of the time, but amusement rides present serious risks for young children.
When deciding whether a ride is safe for your child, base the decision on what you know about your child , not on what a teenage ride operator says or what you see other parents doing.
Can she follow directions and stay seated?
How familiar is he with amusement rides?
Is she easily frightened?
Is he a risk-taker?
How well does she fit within the restraint system?
Treat amusement ride safety seriously as you do traffic safety, water safety, bike safety, etc. Teach your children how to be safe riders, but don't rely on verbal instructions to keep young child safe around heavy machinery. Pay close attention to their actions when you visit amusement parks and carnivals.
!!! I found that funny, so I asked him what he wanted in it. He said "milky"!!! He hasn't had a bottle in years. We had to wait in line to leave. They wouldn't let us go backwards to leave, so as we waited he said "Never mind, I'll just suck my thumb." AND HE DID! He never even did that as a baby! I don't think we'll ever get him back in there.
My kids all rode ToT as soon as they were tall enough and they love it! Of course they love HM as well! But dont use SM as your test point, because all my kids have loved ToT as soon as they could ride, none of them liked SM until our most recent trip. They also love EE and RnR! No brain damage yet 
