For me, the SRK and SupFire M6 have more than enough light for practical purposes. Upgrading to an XM-L2 wouldn't really do too much for me. It seems the only improvement I could make is to make it throw considerably further. The XP-G2 swap might be a good idea. Hell, using a NANJG master/slave setup I could run one XM-L2 and two XP-G2 emitters.