I only recently bought steam copies of the games so more than 90% of my stalker time is with my DVD copies so I can't give actual hours played however I have been using the Steam version of COP to play with the Misery v2 beta and it is currently at 135 hours. But that's a blink of the eye up to my main play time. I'm pretty sure I could be in double figure months for both CS and COP. Not as much for SHOC but LA will probally help it catch up.
Everything you want to know about Degtarev's zone is in the: COP Survival guidehttp://cop.zsg.dk/