the relative common-ness of a watch at this level i think really isn't a big concern. i see many more rolexes than omegas, but that could be my own work or social environment. but over the course of basically five years, i think i only spotted a planet ocean once or twice...even in the business class lounges at airports around the world. most people don't care about watches.... we're already part of a small circle of folks. but wherever i've been, whatever i've worn has usually been unique in that setting. however, if you did spot someone with a poc, wouldn't that be rather cool? a fellow enthusiast! by and large, you're not going to see every third person wearing one of these. no doubt, you'll see the tags and the rolexes.
a practical consideration is how thick the poc is vs the jlc and how well it will fit under under a dress shirt. my jlc extreme world chrono does not wear well with a dress shirt because it's so thick. so it might be worth giving some thought to that. obviously, if you're a cufflinks afficianado, your shirt will post less of a problem, but if you use buttons, it just might. my planet ocean in 42mm (if i remember correctly) never did, but once you start increasing the dimensions....
chris