Thanks Chewy for the answer. Should I upgrade my system to 16 GB of RAM and limit my plugins to certain brands or should I save the money for a new Mac Pro?
Antonio… I really don't know. In my case , I'm holding off on the new Mac Pro (and Mavericks) for the indefinite future-- this old 2008 tower that I got for $1k is doing me just fine, and I don't look forward to the expense of investing in new equipment to make my UAD stuff work (meaning either a Thunderbolt->PCIe chassis or an Apollo).
Were I in your situation I'd definitely go for the RAM, and completely troubleshoot my plugins to ensure one of them isn't at the root of crashing. Also… if there's ANY possibility of your having a bad RAM module-- look into that. Bad RAM can be really hard to track, and reveals itself in all sorts of inconvenient ways. Inexplicable crashes being one of them.
Like you, I get the "video service unavailable" thing every once in a while, and that infernal EuCon crash on exit. But other than that, my Nuendo has been really consistent. And those aren't problems that are going to be solved by a new system.
I haven't seen anything thus far to make, for me , a switch to one of the new Mac Pros very attractive at all.
That's my perspective!