Made a couple of impulse responses of my 412MS. Followed the instructions at: How to create an impulse - GuitarAmpModeling.com
Took all of 10 minutes. Loaded them into the GSP 1101. They sound very good when compared to the IR's of the OS Mesa cab I have. I used an SM 57 and an AT 2020. You need some way to reamp when you do it. My girlfriend about $h!t when she heard the sine wave play back through the power amp of my JSX. Lol.
Instead of describing them to us why not upload so we can try em out?