Aside from pulling power, which I'll get back to, most winches I've looked at use the very same winches with a higher gear ratio to move the 8,000 lbs up to 10,000 lbs. One of the benefits of the higher ratio is, at all pulling loads up to 8,000 lbs, the 10,000 lb winch will draw about 20% less current from the battery. That means 20% longer pulling before the battery depletes, and more electrical efficiency from the winch which means less winch heating. In all my research, the most common rule of thumb was the winch should have a pull of 1.5 times the vehicle's weight, as indicated in this link from Warn winch:
Warn Industries - How to choose the right winch An excerpt from the link: "For trucks, it's simple. Take the gross vehicle weight rating (GVWR) and multiply it by 1.5. For example, if you've got a new Jeep Wrangler Rubicon two door. A quick visit to Jeep's website shows the vehicle's GVWR is right about 5,000 lbs. (2,268 kg). Multiply this by 1.5 and you'll get your minimum capacity. In this case, it's 7,500 lbs. (3,402 kg)." I'm not sure about the 5,000 lbs; the numbers I see are 4400 lbs. Based on that number 1.5x would be 6600 lbs. Another interesting thing about winching is if you have to pull rearward, your trailer receiver is between 2,000 and 3,500 lbs depending on which towing package you have. And if you use the triple snatch block technique to winch backwards a pull on the winch cable of 2000 lbs will produce a pull on the trailer receiver hitch of 4,000 lbs, which exceeds its rating by a good bit. Finally, the intended use for a winch plays a big role. You probably won't need as much winch pull for more casual off roading as you would for pulling your Jeep out of fender deep mud or over boulders almost straight up. I'm in the casual off-road group. I chose (finally) the Warn Zeon 10-s. A lot of the 'why' was because of the higher gear ratio and the lower current draw. Oh, it is unlikely that the 10,000 will weigh any more than the 8,000. E.g. the weight of the Warn Zeon 8-s is 75 lbs; the weight of the Zeon 10-s is 75 lbs.