While i have seen some instances of metal Guide Rods leaving marks on the interior of aluminum frames, it never appeared to be a universal issue. The issue may depend in part on the specific profile/design of the Guide Rod/Spring being used. If i were determined to used a metal guide rod, i think i might try it and see what happens. Worst case it leaves some rub marks on the inside of the frame and can be swapped out for a replacement. The way that i look at it, rub marks on the inside of the frame are not real significant.
While i recognize that some folks prefer metal, i have yet to find any significant asset in replacing the factory poly CZ Guide rods in any of my CZs. My 75 Shadow has a metal Guide Rod but it came with it installed.
I am interested to hear the input of other forum members on the subject.