I have a few amps - Eden WT400 - Aguilar DB750 - Ashdown ABM500RC.
I use the WT400 for rehearsals and small to medium gigs with either an Aguilar GS212 or Eden D610XLT and I use the DB750 or ABM500RC with either the Aguilar DB810 or GS412 for larger shows.
I owned the LMII for a couple of years also and have recently sold it due to non use. I also got on the light weight GAS wagon and that amp sounded good and never failed.
I really feel that amp tonally wasn't as good as the WT400 for what I was using it for and although rated at 500w compared to the Eden's 400w, the Eden has never been out of depth in the specific situations I use it for... consequently, the LMII became stored in my gig bag with my leads etc. and taken to gigs as the back up if one of my others failed (never happened)
So, my experience (and I did A/B the LMII with not only the WT400, but the other amps many times also) has been that yes, the LMII is a good, reliable amplifier BUT, not good enough either tonally or convenience wise to move ME away from the others. I bought an Eden amp gig bag also which has a few pockets etc. and now susequently, I still use the WT400 for rehearsals and smaller gigs AND it goes everywhere as the back-up amp as it's in my "lead bag"
You need more power and the LMII maybe the ticket compared to the WT300? but, you may, or may not be happy tonally?
As always, try the LMII as well as probably the GB 6.0 and if you like the tone of the WT300 but need more power, look out for a secondhand WT550 maybe?
Good luck with your search...