Since you have some money to spend, I'll second (or third, fourth, whatever) the guys above and recommend the Diezel VH4/Herbert for its versatility, and the fact that they have 3-4 channels that can be set up independently.
I will add that I was hard-set to buy a VH4 (not the VH4S...they weren't available), and the local GC happened to have one. I brought my Blue Stripe (not the Coli) and my Triple Rectifier, and I found my Blue Stripe tracked way faster than the VH4, and my Recto had a little more low end (even if it was a little looser without a boost), but the Rectos high end sounded so much more "dimensional", as if there were additional harmonics on top of it. So, I walked out kinda upset because I figured that the VH4 would have been THE amp for me.
If you're comparing your Mesa to a Diezel, in my opinion, it's kinda like a mix of a Mark IV and a Recto. It's a little drier like the Marks, but is voiced to close in on the low-mid Recto/SLO tone.
On a side note, I would highly, HIGHLY recommend the R2 mod on your Blue Stripe. It makes the Mark III a three channel amp. You'll get that Marshally crunch on your Rhythm 2 and really makes it shine. Do it.
Do it naow.