Yeah, I have to say that I'd pick the 5150 over the XXX. Although the Triple X has an extra channel, I found that I really didnt need it, and the tone on the 5150 just felt thicker, and more responsive.
When it comes too micing the 5150 with say a marshall 1960 vintage which is what i have been using... Andy do u use a 57, an inch off center of cone with a 609 mixed in and a bit of pre aswell? or do u just stick too a 57 on own ... ive been trying too get a big guitar sound the 5150 sounds great, but is their any things eq wise too bare in mind when it comes too mixing?
The guitarist i have been working with likes too take the mids out of the amp but it seems this gives it less power ....