I disagree about park hopping. I think fastpass+ can actually help get more done in your second park. When you arrive at your first park in the morning, you are more likely to have lower wait times. By the afternoon, wait times are typically higher - everywhere. Having three fastpass+ choices in your second park means that you can head straight to the park and your attraction - no waiting around until your fastpass window opens up because you could only get the pass once in the park. It also means you are more likely to get a fast pass for Soarin', TT, or TSM without showing up at rope drop (we'll have to see how early these need to be booked once off-site get to pre-book). Do I like being limited to three fast passes? Absolutely not, but I do think it is possible to make fastpass work well (better? not as poorly?) with a park hopper.
My typical trips are only two days and I like to see all the parks. A typical weekend for me is:
Day 1 - start at HS (usually EMH) - leave around noon and head to Epcot and use my fastpasses here (occasionally I will save them and head to MK at night and use them there)
Day 2 - start at MK - leave around one or two and head to AK - use fastpasses at AK and done around 6 or 6:30
I know this is not how everyone likes to travel but it does show how to use fastpass+ while park hopping.