We actually use something like 13x13 categories as the first year (we are about into year #4...) everybody was griping so much about this category vs. that category the commish just said 'we'll just use them all!! Shut UP!!'.
He got xferred to another position so I inherited the job and we used 13x13 (AB, r, h, HR, RBI, SB, BB, K, E, Avg, OBP, SLG, OPS for hitters and IP, W, L, CG, SHO, SV, HR, BB, K, Holds, ERA, WHIP And K/ 9 for pitchers). It seems to work well and the league is pretty competitive, w/ lots of close matchups, lead changes, etc. Nobody has bothered rolling pitchers or benching them really, a couple of people had some success using tons of P to win the volume but only for a couple of weeks as sooner or later, they get shelled and slaughtered. W/ more cats, each cat isn't worth quite as much so about the worst thing that happens is speed guys don't have quite the same mojo as in 5x5. We did a 5x5 roto one year for the second half and it wasn't nearly as entertaining