IdRatherBeSurfing:-
Probably a bit late but I just stumbled across your discusion. Any way having gone from a 7'6" x 22 3/4 x 3 minimal to a 6'10" x 20 x 2 1/2 fatboy, for similar reasons to what you are stating, I can say that I have found it a bit tricky at times with the smaller board and have found myself going back to the 7'6" recently. I'm about the same weight as you and only a couple inches taller and although I can get out back, paddle and catch waves well enough on the fatboy it is harder work than on the 7'6 and so that equates to less waves per session and less progress with the stand up surfing, the fun bit! I'm personally considering selling the 6'10 and going for something slightly bigger maybe 7' x 22 x 2 3/4 so that the extra width and thickness might just give me a bit more speed and i can start working on my arials
Hope this is of help fella, happy surfing!