If they're just replacing the amp, you're getting the same type back. I had a Mark 1 of the EP350v3, and they replaced the whole sub when I had a defective amp. The new amp is much, much smaller than the old one and the "boot" is now built into the cabinet, not surrounding the amp. Personally, I'd call it a v4 by this point, but I ain't Axiom.

I am the Doctor, and THIS... is my SPOON!