the other thing i'd say is that, assuming the vm combo reacts similarly to the head, if you can't turn it up to deafening volumes, the screamer would be the better choice, if you ask me.
as timi says, though, it really depends what you want it for. you'd really need to try it- judging from this thread alone, there are several people who absolutely love the vm, and several who weren't impressed at all- only way to know which you are is to try it...