Hi Aj,
Computer is a 2.6g mid 2012 mb retina (10,1). Agree that £80 is a lot to shell out, the only downside as far as I'm concerned, esp. as the Virus isn't cheap to begin with.
I'll be honest and say that the virus in Ableton still isn't absolutely perfect, (sometimes timing strays a little and it's well sensitive if you have put either machine to sleep or loaded the plugin in another host). Nowhere near the initial problems that I had though.
I generally use the audio outputs and the plugin with the 'Live' button lit for sound design, switch to the USB outs for rendering, and good old midi input without plugin at all for totally live stuff as that seems to be the most reliable timing wise.
Hope it helps and good luck!