I like spokeshaves a lot, dont know how much you are willing to spend...
I have had succes with the older stanley spokeshave (nr 151 if I am correct), not so much with the newer ones. You definitly need one with a flat bottom but I bet you already knew that, I dont have experience with low angle spokeshaves.
When using a spokeshave on the belly of a bow (lets say a flatbow) try to make the belly a little round, that way you wont experience any chatter of the blade.
Stefan