Just unlocked SEE - what now?

Depends who else you have with him. A Relic DR, DBastila, and Malak will help a lot, as will Wat Tambor.

Non-Ult SEE should be able to take out JML, and will walk over any GAS 501st team solo. But he really needs his ult a lot more than, say, Rey or JML does.

have most of the usual suspects except triumverate (DR/Bast/Malak/Wat/Gideon/piett (and a couple other troopers) at relic, along with the sith you need for unlock (Vader, Dooku, Sid, Maul, Palp) Armorer is lower gear but zetaed