We did that last year. Our oldest was a senior in high school, and we're not local, so you do what you have to do sometimes, with the rare schedule openings that you get! No regrets. Not counting ticketing/security, Downtown Disney was the worst for crowds, IMO, followed by Tomorrowland. I felt like you could get away from people pretty much everywhere else, if you wanted to.
We used mobile order, which a LOT of the day trippers apparently aren't aware of, b/c we had near-instant returns almost every time and would walk past huge lines of people waiting to order in person. We had a few ADRs as well, largely b/c I wasn't really sure if we'd need them that time of year due to excessive quick service waits (esp with allergies).
We had
genie+, which helped a lot. I have teens only, and they were morally opposed to rope drop. We got pretty close on our first day, but the crowds were horrific. We did the shocking thing and decided to arrive more like 9:30-10am from then on, and it was much more pleasant. YMMV, but with ride breakdowns happening all day long and so many people there anyway, it only meant we lost a couple Genie+ slots. Sure, some things will be booking very late at that point, but honestly - it didn't end up mattering, due to the ride breakdown multi-passes. Also, with all adults/teens, we had more night-time staying power, of course.
I guess the biggest risks are really tied to expectations. Ex: if you have a big Space fan, they aren't going to get on that a few times a day. (Heck, we had a hard time with once, b/c it kept breaking down.) If everyone understands in advance that lines are going to be long and you have to be flexible, you'll be ok. Make a list of priorities and work around that.
In terms of benefits: 1) it was great to see the Christmas decorations and HM overlay for the first time. We could never take teens in early Dec or some 'slow' time with the decorations up. 2) It rained some (which worked to clear the parks out one evening), but the temp was very pleasant the whole time. 3) It felt like it was staffed up to meet the expected crowds. (This sounds odd, but we went to WDW in a weird off-season time in Feb a while back, and lines were sooo sloooow b/c they were lightly staffed. It was somehow more painful, to have so few fellow guests around but endure so much waiting.)
. I want to hear all the pros and cons of going during this time-- risks, benefits, etc ..
