Winter tires, unlike summer or all-season, do not have the US federal wear rating on them. So, any comparison on longevity would be subjective, and uncontrolled. FWIW, the R2's were designed as low-rolling resistance, eco tires, so should be similar to the Blizzaks in economy. SOrt of depends on if the ice and snow grip improvement is worth the investment. In the comparison test, the R2's were the easiest to control in lousy conditions, too.
In my case, I got a deal on the OEM versions when I bought my car, so did not look hard at the alternatives. When it comes time to replace them, I'll probably go with the R2's. I don't think you'll go wrong with either set.