Yep. Sigma 1 and Black are close enough to where you wouldn't have a bad nor vastly different time with the former. However, Sigma 2 is fundamentally different from vanilla 2, and it isn't a subjective nor opinionated matter. One can prefer Sigma 2 to vanilla 2, that's totally fine, and I'm happy for that person. But, the former is vastly different to NG2 standard in nearly every single way, and in my honest opinion, for the worst.
It's still the same game at its core, there are significant differences but far from being enough to make them incomparable.