yeah, i'm a warn winch guy too. i run a powerplant on both of our JK's and they have served me well. as mentioned, customer service is top notch and really, a good warranty don't mean squat when you're on the trail and your winch ain't working.
regarding capacity, the rule of thumb is typically based on the weight of the vehicle x2. so, if you have a something like a TJ that weighs about 4,000 lbs, and 8000 winch would be more than enough. a JK is just shy of 5,000 lbs from the factory and so, a 9500 or 10000 winch will get the job done.