I've done dimensional studies in the past on stripping and reanodizing. Anodizing is a conversion of the aluminum base material to aluminum oxide. The anodizing layer is partly penetration and partly buildup. When you strip it, you lose the penetration part of the materials. Reanodizing just repeats the process, but there is less material than the first time around. In general, expect to lose about half a thousandths of an inch per surface. Rails will get thinner by about a thou, slots and holes will get wider by about a thou. It's plus or minus a few tenths of a thou at every step, so YMMV. It may be that a thicker coating like NP3 or Cerakote on the slide could net out the difference created by loss of material on the frame.
At the end of the day, it probably doesn't matter much for the slide rail fit.
I'd be interested to read if Mr. Langdon has gauged action pivot pin hole diameters before and after. If those diameters grow, it could lead to a very slight amount of slop in the mechanism. Nobody's complaining about this, though, and as noted, if the pins are NP3'ed, that could net it out perfectly, or even tighten fits up a hair.