I own the pre-2005 KSC MK23 (meaning it's more rugged than the 2005 version, but harder to find parts for) and I love it. No metal slide (want one it'll cost a good $160US) but it runs fine off propane and fires a 0.28g BB well past 150ft straight.
I fixed some USP mags for Lt. Korv, and I had his FMU KSC full sized USP here to test fire, and I fell in love with the thing, it's like a smaller USP, kicked really hard, really great gun (except never tried it for range, and the accuracy wasn't as good as the "plastic coat hanger, 3-4 hits out of 10 at 30ft accuracy" of my MK23. So I'd scoop up the USP full size (avoid the compact) if I went for another pistol, easier to find parts and holsters for.
BTW, the LAM for MK23 is LAMe.