I didn't know what a snatch block was, but after finding an image, it would basically double winch power by doubling up rope right. Finally after 20 years, that Statics & Dynamics class I took in first-year pays off.
Sheamus,
Just had a winch issue today, that I'll post separately. I think a 3,000# winch is the bare minimum for a side by side. I've had 3,500# and 4,500# winches on mine. My primary use is to lift my snow plow blade. In the rare, but
very significant, circumstances where I've had to winch myself or some one else, I never suffered for power, it was always that my machine didn't have enough weight to pull (for example) the jeep out of the ravine.
If you stay over 3,000# at a minimum, I think you'll be fine. At the same time, if it's just a few shekels to get a higher pull capacity, then I think its money well spent.
If the good lord has blessed you with a Tractor Supply nearby, their 10,000# snatch blocks are a great deal.
And I'm still waiting for my statistics class to pay off.
Over.