I think once the right amp and cab are used, the artist sound should come easy enough.The Carcrash sound is just the 30th anniversary head boosted.
It sounds like the old Carcass sound because that's what they used rather than me setting up a Carcass sound.
Also, the MKV in MKIV mode with high gain and bass through mesa cab nails the Metallica AJFA sound, because it's the right gear rather than me chasing that sound in particular.
Once the sound is good with good mic placement and good mic pres and converters, it should be easily tweaked.
Oh, in that case, make sure you leave some helpful hints on your website, I think that will help people like me decide which of your amp packs to get. I really plan to get this amp pack in particular, it sounds amazing.
You know, something like "Sounds like" and then maybe youtube links to songs, etc.