had shimano xt, went to sram x9 and was wowed by performance, crisp quick changing. Rear mechs were fragile tho, broke 3 in 9 weeks, one short cage shattered! Dodgy bottom jockey wheels were to blame, replaced with £3 shimano ones and they were fine.
Gone to SLX as a result of a whole school change to shimano form avid/sram (had matchmakers so made sense when i got rid of the juicys)
SLX is very slick shifting, not a clicky as sram – more smooooth imo. Before anyone says new cables etc – the sram had new cable before i swapped so i can directly compare the performance.
SLX for cheap smooth shifting imo (and rear mechs are nearly 50% cheaper)