Do it Ike, you'll love it!
The problem with sizing up, as you no doubt know, is being able to do something (move seat forward, put a drybag in the bow) to keep yourself wedged in during whitewater. A bigger boat is also heavier. On the other hand, in addition to stability you'll have a bit more room to lash things on (ie a mountain bike). I've been happy with my yak, which is "classicly" the right size, and would by it again. The weight savings is good.
The Shuna rocks. So, so good. Treat it like a good canoe paddle and it'll last. Not as durable as a nylon blade, but for me so worth it. You paddle water, not the paddle with it. 210 is a good length.
I prefer a foam PFD. It provides more mental security, and makes a nice camp seat and pillow. The one mod I did is to cut the back open, remove, the foam, cut it in half, and put both halves into the upper half of the vest. This keeps it from messing with the backrest and deck.
I don't know of any drysuit that's cheap or light! Kokatat has a great reputation, and I've been happy with my bare-bones model, but it takes up more space than the raft. I don't use it that often. Neoprene socks, some Kokatat Deluxe Paddling pants, a raincoat, and extra core insulation (a thick fleece vest is great, especially as the one flaw of a rain coat is letting your sleeves get a bit wet) is my usual approach to wilderness whitewater trips. Along with trying really hard to not swim. The pants are great, they keep your pants dry very well, which makes a surprising difference.