IMO there's lots of space wasted on the FM3. Unless they really needed that space for the circuitry, I fail to see why it has to be that bulky (or not have, say, 2-3 more switches, which would fit easily.
As far as the integrated PSU goes, in general I'm all for it, but on a larger pedalboard it's sometimes turning into a disadvantage as you may have a powerful multiout PSU already, good enough to drive some more demanding units as well. Wouldn't work with the FM3, so you'd always have to deal with an additional full size power connection.