so far I have tried the 16T that came on the bike. it was on for about 10K miles. an 18T that was on for another 10K. the 16T back briefly (just playing) and now a 17T. The 16 and 18 had the good and bad points previously mentioned but where both useable. The 17T seems like the best fit for my current riding with the least amount of compromise.

05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter