For transmission depends if you care about weight or not, having used SLX mechs and shifters for 6 months + I can’t really justify buying anything above SLX now (unless it’s going cheap on here!)
For the forks RS REVs were standard fit on the 2011 Comp; I have the basic RLs and they seem perfect to me. I don’t have travel adjust and find the bike climbs perfectly on steep techincal ascents with 140mm. You may be better of with 2011 / 2012 forks that have postive and negative air inputs rather than the latest Revs with only one air input as the newer forks in my opinion lack adjustability and feel somewhat dead.