Ph.D. or Cat SL 1

I have a CAT SL-1 (finally fixed) :). Rogue M-150's, Magnepan 3.6r, VPI TNT 3 with JMW 10 arm and Benz H2 cartridge. I have been thinking about swapping the CAT (which is an original with serial number in the 2000's...for the Sutherland Ph.D. Anything I should know?

I hesitate to move away from tube into non-tube of any kind... no one sells the Ph.D. in my area...so I can't demo one.

Any input :)

Erik