I do not own a Sebatron either.....yet, I might add.
But I do know that the GT Brick is a stripped down version of the GT Vipre.
Now as far as the Sebatron VMP goes, it's not a stripped down version of any sorts. So based on that general knowledge, I think it's fairly safe to assume that the Sebatron has more flexibilty and more in common with a Vipre than a GT Brick.
Hope this helps

i think the brick could use a type of pad control to stop it from distorting with high output mics. we had the opportunity to borrow one a few months back and compare it to our sebatron.i think if you can purchase one of those shure in-line pads that could be a good idea. the seb can get cleaner than the brick depending on how you drive it. the pad control and eq are the real bonus.