Fox made a great name for themselves a few years back when they came out with a product that was head and shoulders above the rest, but the new RS stuff is incredible and in my opinion has really taken much of what Fox was praised for and made it better. If you have a chance to see both the forks taken apart, you'll see the difference. Fox's internals are pretty complicated with lots of small parts, where the RS stuff provides the same functions but with a much more elegant and durable design. I'd really recommend the SID, you won't be disappointed.