Here's the only quote you need from a tester. It's funny to read the folks saying how wonderful it was for them to change FP+ times on the fly (not the poster I'm quoting, but others). OF COURSE YOU CAN. You were part of a TINY test group.
I'd love to hear what the "ugly" was that Disney is hearing. If anyone is complaining about being part of this test, they're from Mars. It was like hitting the vacation lottery in the middle of the busy season.
I wonder if Disney is asking the question this poster was answering "Would you have been satisfied without your normal FP access?" If they aren't asking that question, they aren't looking for any real data.
And as for just planning that many people are too ignorant to use normal FP now, and figuring the same for FP+. Didn't Disney already say they will give folks FP+ if they don't pick them? So at least the on-site guests will get FP+ always. And when you enter for the day with a ticket you just bought, you will be assigned 3. Three horrible ones, but 3 FP+ all the same. They pretty much have to. Imagine a guest from the Comfort Inn on a once in a lifetime trip showing up to buy tickets, and realize that everyone else has FP+, but they have nothing. Disney will have 3 times the highest daily attendance number of FP+ available all the time. Even if your 3 are Hall of Presidents, Carousel of Progress, and the mind-blowing Mickey's Philharmagic.
Jason