well, changing wheel hub, means also redoing alignment, so it's not like just changing wheel, but of course dropping tranny is more work to do (hence the reason why i used one of gearbox related work as opportunity to put some tranny/clutch related aftermarket goodies in, eg. syncrotech synchros/velox clutch fork&pivot .. and new TOB bearing just for any case. Had no problems even with previous being original old "bad" one, that lasted w/o any glitch for me much longer then both TOBs for you and even including bad track abuse (eg. initially not rev-matching downshifts via heel&toe, and sometimes using clutch drops to intentionally cause rear slide) (hence my guesses about bad luck
or something botched up during replacement rather then generalization about all TOB bearings of twins being crap). But it being cheap, for peace of heart, why not preemptively replace at any rare occasion transmission is dropped).