Damn.. I am becoming a sucker for mice. I just got the Steelseries Rival and love it. Didn't like the Raw at all, but this one has been phenomenal so far. It's replaced the Corsair M65 which I really liked too. I may have to search for this one. Did some reading and watching after you mentioned it and now you have my interest.
I have a Steelseries Sensei, and it's great. A bit too slippery (which your Rival solves), but the actual tracking is great - I keep it in my messenger bag every day, for when I might want to play games on my laptop (especially handy with all the work traveling I do).
My biggest gripe with most mice is the damn tracking. It boggles my mind how many "gaming mice" just have absolutely piss-poor tracking/sensors. Pretty much every Razer mouse I've used has been garbage - I constantly "overshoot" my cursor and miss my target because of acceleration and other "features," and my mouse just generally hops too much. After a third Razer mouse in three years (ProClick -> Orochi -> DeathAdder), I swore them off forever.
I've tried Corsairs - they feel weird as heck. I've tried MadCatz - the build quality is abysmal.
I always seem to come back to Logitech. They have, IMO, the best build quality, the best comfort, best button placement, and most importantly, best tracking.
And so, with all that said, if you're happy with your SS, I don't know if the PC is going to be a huge upgrade - they're both good. But if I had to pick, I'd pick the PC every single time.