The longest it has taken me, in 4 rides with DME, has been 85-90 minutes. Most of the time it has been closer to 65-70 mins.
Okay, let's list out the pros and cons of each...
Towncar....
1. you'll have to get either a stretch limo or an SUV since 5 adults are not going to fit in a regular towncar
2. you will have to wait for your luggage at baggage claim..could be 10 mins, could be 25, no way of telling.
3. it will cost you
4.you will go directly to your resort
5.you don't have to share with anyone but your friends.
6. you will be able to stop at a grocery store on the way
DME....
1. you do have to share with others
2. you will have to wait a few hours for your bags..most likely you'll have them by11:00
3.it's free
4. only take about 70 mins to resort from deplaning
5. no schlepping your bags
6. if you need groceries, you can use wegoshop.com, or gardengrocer.com..either one will buy what you need, then deliver it to your resort, for a small delivery fee, usually under $15.
So.....what would I do? I would book DME. I would have everyone in the group pack a carrryon bag with nightime essentials...pj's, toothbrush/paste, hairbrush, clean undies, maybe a change of clothes. And don't forget to have all you travel documents with you, as well as park passes, reservation paperwork. This way, if your bags do get delayed you can hit the sack and not worry.
But, I know this is a very personal preference....different people have different needs. You will have to decide what is most important to you.