We just got back yesterday as well and from your reports, I am glad we opted to go to MK on Monday instead of Tuesday. We agonized over missing the fireworks but we got a lot done on Monday before the
MVMCP started. At 4:00 it did get more crowded and the lines got a lot longer.
We never waited more than 10-15 minutes in the FP+ lines (even for popular items like 7DMT, A&E, Soarin', etc.) and were able to get more than 3 each day which was very nice, but I did notice that the non-FP+ lines were longer than usual and you could see that people with FP+ had a much higher priority than those in the SB line. We didn't notice too much of a change in the wait times in some of the less popular rides (IASW, Barnstormer, etc.) or rides where people didn't use their initial FP+ but we waited forever for Space Mountain while watching the FP+ people just walk right through. The kids decided they were brave enough at the last minute and the posted wait was 35 minutes but we were in there well over an hour. (as an aside, we almost missed our 7DMT FP+, but were told that they have a built in buffer after your end time. Not sure if it is different on each ride, but the CM at 7DMT told us it was 15 minutes.)
It is clear that the FP+ people have a much higher priority than the SB line, which did seem to make the SB line move much slower. On Pooh Bear, we didn't move at all for a good 5 minutes at a time while they let on FP+ people. But if crowds are huge (which it sounds like they were on Tuesday), both lines are going to get backed up. I can't imagine what the SB lines were like if the OP waited 25 minutes in FP+. We did learn to move fast if there was a break in the FP+ line and they started letting in SB!
Overall, I didn't think it was a bad experience for us though. We got there early and rode some big ticket rides (in MK - Splash Mountain, BTMRR, HM, etc.) and had our FP+ planned for middle of the day (10:00-1:30), grabbed another FP for later, then ate lunch and jumped on lines with lower wait times and then hit some more big ticket rides later in the day (which was hard in MK on Monday since from 4:00-7:00 there was an overlap of the party folks and the non-party folks and it got real crowded.) The only frustration was getting in a not so longer line and not moving at all because they were letting in all FP+ people. The lines used to at least always move at Disney which helped it feel better!
We went to the EasyWDW recommended parks each day and I think I am glad we did. We didn't have huge crowds until Tuesday in EPCOT and Wednesday in MK. But this was definitely not a slow time to go.
