I've used the Omega rings for almost 2 years now. Never had a problem with them and the weight isn't that big of a deal. I've switched to the SMC rings for simple economic reasons: I'm cheap. The REI rep told me that he used the SMC rings and really liked them, and being a hard sell I quickly bought what they had. I've spent this weekend using the SMC rings and to me they seem to "bite" better on the webbing. I'm sold on the SMC rings now.
Like Taz said, REI doesn't charge for shipping to the store, so I'd go that route. My .02 worth