Any reason not to? From my recent experiences, it seems like a rotary makes for an excellent pump. Twice as efficient as a reciprocating, able stand much higher static pressures, great start-up torque, and compact size. What else could you ask for?

Perhaps you're going to use a Scroll instead?
Well, simply put, height, though not so much in this case, but also noise. Rotary's are lovely and all, however though this version will be much too big for a single stage case, I do want to get it down to that sort of height.