31pt Vader just doesn't do it for me anymore. I feel like he needs to punch his weight or at least contribute AND SL. Proton Rockets gives him a cheap way to do that. At 34 you could run him with SL and Procket... But I still prefer outmanuver + EU and then Procket if I have 3 pts. A 3 dice swing in your favor for 3pts is hard to pass on.
I used to run SL vader with Stabber, PTL Turr, and an Alpha. Was a great list back in wave 2 and is a great learner list.