It would be really cool to have that speed controlled by the files, and I admit, until this thread started, I assumed the Desktop did have control of the spindle speed (as "software-controlled RPM" was always something I associated with the magical world of spindles - I still use a PC router on my Buddy). And at $7,000+, it's certainly at a price-point where you would think it could somehow find its way in there.
I ordered a Desktop anyway, so obviously not a deal-breaker for me, but it would be a great option in the future.