ElGuano said:I think the biggest consideration here is portability.
Yep. I've taken the P2 on airplanes (real airplanes ;-}). Without disassembling the 550, I couldn't get it on-board. The P2 is definitely handy for travel. The 550 not so much. The 810 is worse (by at least double). The P2 will always have a place.