I would. As long as it's a Quad-Core Mac "Pro" that's close to $1500, I'll but it.
That's the problem though...
the Nehalem i7 2.66 and the Nehalem Xeon 2.66 are comparable in performance, and even close in price, yet Apple offers the 2.66 Xeon for $2500 and anyone can walk into Fry's or Microcenter or fire up newegg or mwave and build an i7 920 for $1250 with a 1TB drive, 12GB of ram and a 4890 1GB video card.
There is no reason to offer single CPU Xeons at 2.66 or 2.93 and charge such a crazy premium for them. The dual CPU models do require the Xeon processors since the i7 does not support dual configurations.
the lineup should be something like:
i7 2.66 $1500
i7 2.93 $1800
dual Xeon 2.26 $2500
dual Xeon 2.66 $3300
I did not run any actual numbers, so those are a little off the cuff, but close to what I feel like a good lineup would be...