Exciting news! Are you using a variety of speakers or sticking with the M Britt standard?
A little of both. As a rule, I usually start with my usual speaker setup, but with some of the amps I used different cabinets while searching for sounds. One of the packs I'm working on is a heavy pack with a lot of gain and I used a few different cabs for those. For the clean/mid gain/rock stuff, I keep landing back on my 3P cab just because I like the way it sounds, but there are some with different cabs.