You'd actually have to ask CQBR. I just picked this up from him last week. Haven't had the chance to shoot it yet, but it feels quite nice. The recoil spring is a little splashy for sure, but otherwise it's not bad.
Yep, both Infinities are fully upgraded. The Champ .45 has a shooters design metal slide with a Guarder one piece steel barrel and chamber. It's also got a reinforced loading nozzle, a sheriff hammer and a spring set to match the extra weight. The 4.3 has the slide and barrel, along with the loading nozzle. Never got a chance to get a steel hammer when you could actually find them, but the stock piece is just dandy.
It shoots well, but doesn't finish a full mag of bbs on one charge of gas. I bought it used, and the guy I got it from had played with the mags a bit, and I figure he might have done something to reduce its gas capacity. I'd like to get a couple of new mags for it, but I don't use it much so it just hasn't been worth it for me.