SRS will have an experience cap based on your level. At this point, you should start leveling elsewhere.
I am assuming that the GM knows your role and lvl. Depending on those 2 things, srs and if you have others to help you or not, srs is best til IS 1-2, then try to lvl in llgc til later lvls. I normally go to llgc, but only on 3x events, which are limited to holidays here in the USA (which is sad because there are more than 1 country that plays this game.) USA based servers or company shouldn't be the standard for events. It's way faster to lvl as a ck role that uses phys smg as well.