|First off, I would do a little more in-depth research on the xen server. I don't beleive they're capable of what you think they're capable of. At least, I doubt very much you can run 10 PC's and however many servers on a single Xen box. |
While I think you could run more instances of VM's in a vmware box than you could a xen, you still couldn't run 10 clients and citrix servers out of a single vm server. They too have a limit to how much they can do at one time.
Second, a KVM switch, or two or three, is probably cheaper than the licensing for citrix and would clean up all your K/B's and mice.
If it's a test lab, it's not permanent so why are you worried at all about the "mess". Do your labbing and dismantle it when you're done.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.