We bought a bubble bum for our 5 year old for our past trip in Feb, and will use it again in May. For our soon to be 2 year old (birthday in 15 minutes!) we rented a seat from Dollar (I think it was dollar). Our upcoming trip we plan to take a seat for him to ride in in the plane, since it will be his first time to not be a lap infant and I'm worried about him wanting to be in my lap for takeoff. I'm hoping sitting in his carseat will make him realize he has to stay in it, just like when he's in the car.
So our experience with that - I felt like the bubble bum was just an option to make us legal, I don't know how much safer it seemed. I guess it must have been somewhat safer, since it would have raised him and thus raised his seatbelt, and it is approved. So maybe it's just a mental thing, and I'm not used to it. Having said that, we're using it again. In an ideal world we would have his car seat from home that is huge and practically has airbags, but even with just 2 kids we can't handle all of our stuff plus 2 car seats. The rental car seat seemed fine, but for some reason they removed the LATCH restraints, which is how we have always attached seats (well, I guess we have had to do it with seat belts at some point, but not enough to feel comfortable). The top tether was also too short to use, which is not required but given the rest of the story I would have rather had it (our son was rear facing). Se we spent a good 20-30 min trying to get the seat in tight enough, and honestly I'm pretty sure we never did get it in nearly tight enough. No instructions other than those on the side of the seat. I as ready to either cry, throw the seat, or tear my hair out. Finally my DH, who is usually the most paranoid, safety conscious person ever, said that's as good as we can get it, it must be in right. Honestly, we both have advanced degrees and I felt like a dummy trying to get this thing in. That experience really is what pushed me to decide to bring his seat this time, it will be safer and easier (I hope) on the plane, and we can just latch it in and go when we get there. Otherwise I might have just tried him in a seat belt on the plane and rented again.
By the way, we got our bubble bum on
amazon for cheaper than in a store, so check there. We did take the cheapest color, which had some neon involved, but we only use it on vacation...