Hey P!
Reaktor doesn't crash live for me. Hasn't done so since upgrading to 5.1 (touch wood!)
Good call regarding soundcards - yes, I do plan to route audio back and forth between the two

But then there's the good old question of which sounds to send through, and from/to which programs...
I have thought of simply using my old laptop as a synth rack (perhaps reaktor standalone with a Max front-end?), running an ADAT line back and forth....oooh, the possibilities are quite staggering, and I'll have some serious computing power to do it.
BTW, so far the specs are:
ThinkPad 15.4", centrino 1.5ghz, 512 ram ->probably with a Motu828 mk1
Vega 14" CoreDuo 2ghz, 2gig ram -> m-audio 410
I will definitely get a "buddy-set" of audio interfaces when the cash is there... but I'm getting the case done first, so it won't be for a long while, I suspect.
Is anyone here running tandem rigs with synths on one and Live on the other?
mbp 2.66, osx 10.6.8, 8GB ram.