Cubase 6 has so far been the most stable DAW I've ever run on PC - I've just mixed an album with it running Powercore
and UAD's maxed out and VCC
on every channel and I have literally not had a single crash or even the slightest anything is 3 months of solid use!
Steinberg seriously have the stuff together these days, I have to admit I find Cubase 6 to be a very high quality product in every respect.
Quality is something I don't mind paying for. That said, it doesn't look like 6.5 is going to have proper dedicated VCA style groups, which at this point is the only feature they are going to get me to get my wallet out for, I can continue happily on the current version and pass on 6.5.
Looks like I'll be waiting for version 7!