Thanks for the input about the output! We agree on the V30 - I don't like the presence spike in them either. From what I've read, the 212 amps and cabs from L6 have one of each - GH90 and a V30. That might not be a bad pairing.
I have a DT25 112 combo, which is a lot of work to swap speakers in. I'm auditioning them in a 112 cab I have, and when I find the right one, I'll swap it in. The trouble is, with so little clearance between the amp chassis and the speaker (less than a 1/4 in some spots), speakers that aren't built exactly like Celstions might not fit.
I'll also agree that the stock speaker isn't the worst I've heard, but it's a touch too peaky in the lower mids for my tastes. So far, the only other speaker I've tried is a Celestion G12H 75th 30 watter. It appeared to be a little to the other extreme in the mids - lacking them a bit.