Guide rod specifically, not a big difference between the two, but the finish of the LCP comes down to two points; how are you going to carry it, and how bad do you sweat.
Most people tend to carry the LCP in a pocket holster. And if you aren't in A/C all day, everyday... your pockets can be sweat magnets (I know people who sweat like hell in A/C). For me, my sweat is about two steps shy of battery acid. The first time I put my LCP in my pocket, rust started within two or three days (I tried oiling it periodically, but stopped carrying it until my solution came up). Slide, itself, was bad, but so were the CT grip screws.
I sent the entire gun and all magazines to CCR for Cera-Plate (along the lines of NP3). Only part they didn't do was the alloy insert, as they don't plate alloys (had to send the frame back as they needed replacement pins before attempting to take it down.
As a pocket gun, I'd definitely recommend stainless (corrosion can still appear)... if not some type of heavy duty finish. My 642-1 was done in NP3 Plus, and I specifically sent them the 9mm conversion cylinder to match it mainly for corrosion protection (does look cool, though).
