well ive been using the new clutch tension thingy xt mech and havent heard a single chain noise so can verify it seems to be doing a decent job. im still using a silent guide which is now the noisiest thing on the bike… however id never go without at least a bash as id rather be smacking that on rocks than my chain and chainring.
without a clutchy thingy, hmm i suspect youd be stopping often to fit chain, and possibly bending a chainring when you clamber rocks or just hit em!
so in summary, get a clutchy wotsit mech, and at least a bash to catch rare errant chains / bash things