Frankly, I'd have to emulate someone who gives a sh*t, to take a position on this one.
If it works, I'm fine with it, no matter what is under the hood.
I actually prefer the real hardware, even though it can be a pain. But WinUAE can also be a pain with all the options.
The best software emulation (for me at least) is Amithlon, as it's very close to the hardware, and actually uses some drivers that hit the real hardware.
Anyway, I think the Vampire will be in the same boat - it's a FPGA programmed as a super fast 68k. And it also uses real hardware and drivers. So to me that probably will be like Amilthon, in a way, in terms of how it feels. I have a Vampire 500 on order but I'm sure it will be a long wait still.
Darren