HI - we have a quest and while I like it, I really don't love it because of the tipping factor. We got in in January when dd was 10 months. She will be 14 months when we go next month, and I plan on taking my (much bulkier) Metrolite instead of the Quest (even though the Quest was purcahsed with the idea of it being our vacation stroller). I just HATE the tipping. DD won't sit in any seat (stroller, high chair, etc) for long periods of time and when she starts fussing and squirming to get out, I can never grab everything off the back AND her w/out it tipping. We have the universal organizer (without it, I don't think I'd like the stroller much at all - the storage basket is SMALL and nearly impossible to access if the seat is reclined - and I bought the quest b/c of the "nicer" recline!). I really don't want to sound negative, because it is a nice stroller, the handles are nice and tall which is great for me and dh and the fold is super quick and easy - and it is LIGHT and SMALL - but to give up the ability to "fill" the basket with the diaper bag/change of clothes/baby snacks and to give up our cup holders and her snack tray and the larger sunshade (though we use a ray shad also anyway), just doesn't seem worth it. We had our Metrolite in Disney when she was 3 and 7 months and really only struggled the first trip with the busses (and that is only because DH wasn't "good" at closing the stroller - I made him practice before the second trip - and practice with his hands full with the bags, etc. (sounds silly, but it made a HUGE difference - he got a routine and no problems after that!) Anyway, we also drove a lot more the second trip (rental car) - with the baby, I didn't find the buses much more convenient than driving - other than the Magic Kingdom (and we would walk to Epcot and MGM) - so I guess we really only drove to AK and Downtown Disney or other resorts (where the busses would be rough anyway!)
Anyway, sorry for SUCH a long response, but I just wanted to give you my POV. Also, I should add that we have flown with our "bigger" stroller 2x also and that was NO PROBLEM since it was gate checked. I think the tippy quest would bother me at the airport also - since I liked being able to stow our carryons in the stroller basket. And like I said before, I think this may be a bigger issue for us b/c DD won't sit in the stroller for long periods of time and when she decides she wants out, SHE WANTS OUT... but you also have to remember that you are going to be taking your child out for every attraction - we chose to leave "nonvaluables" in the stroller (change of clothes, diapers, etc) and only take the bare minimums on the ride/attraction with us (camera/sippy cup/wallets/etc). If you are a "light" traveller at the parks, then I guess it wouldn't matter much, it might fit in the bottom basket, but if not, do you really want to have to take those onto the rides??
One final thought - I wish I would have realized how easy the stroller tipped before I bought it- I would have bought a volo instead - because it is even lighter and has a shoulder strap. It would have been great when we were out and only needed the bare essentials and I think the shoulder strap is a great feature!
Hope this helps!