You'll have no problem with second tier attractions.
If you want to switch around TSMM, Soarin', Test Track and Enchanted Tales, good luck!
I'm on MDE right now, and if you wanted to switch things around for today (and remember the park doesn't even open for another half hour), you are out of luck for TSMM (no FP+ available), you only have a choice of later evening for Soarin and test track (the 6 and 7 o'clock hour for Soarin', and 8:45-9:45 for Test track). For Enchanted Tales, well, MDE is not letting me into Magic Kingdom FP+ pool at all (stupid glitchy system!!!), so that you'd be out of luck as well.
Just for fun I checked Sunday for Enchanted Tales (since it won't let me check today), I can go at 10:45-11:45 or 5:15-6:15.
Everything else seems OK, but those attractions were never a problem under the old FP system anyway.
Same day availability is pretty much a joke when it comes to any attraction that had availability issues prior to FP+, this is just a shell game. There are the same number of winners and losers. Good luck to everyone.