You might look into upgrading the CPUs in your current Mac Pro; I've done that with my '08 Pro (from 1.8 to 3.2) and it make a big difference (faster, lower power use and runs cooler).

Of course the new Pro's offer quite a bit that is compelling, but you might be able to put off a large expenditure for a couple years upgrading your current system. (I'm basically wanting to wait until the cost of TB accessories come down, as well as being able to save up to make the purchase in cash vs. financing a new Pro).

Of course, if a new pro makes your work more efficient, productive, etc. then that may pay for the purchase and justify getting one now :)

Nice blog, enjoyed reading the articles.

-l

OH, and thanks for XRG, I have it as a startup item since I find using it so helpful.