The Gunslinger is not op or up, simply you must be well equipped and very fast in skills execution: i am rank 65 with 671 expertise (8 battlemaster pieces and others champion) and with a healer you can make a huge amount of kills. After leg shot you only have 3 or max 4 sec to enter in cover,to use your rakata and skills buffs, and your rotation, it require to use key numbers and not mouse click. Trickshot have a 1,5 second window for to be used after scoring a critical hit, it is a class for really fast players, infact in the entire republic i only had saw a very few liv 50 gunslingers.
p.s. gunslinger's distraction is understimated in any case, you can interrupt all actions every 12 sec and denied the skill interrupted for 4 sec, in 1v1 it is a great advantage,i repeat: it is a class for fast players.