Hemo will be competitive, probably not better unless you have issues getting backstabs off. When you consider the energy cost difference, and the fact that it gives you more poison procs + combo points, it comes close.
I think it would actually come out slightly ahead in damage if you also took that rupture refresh talent against teams where you sit on a target with no downtime (like a test dummy), but thats a pretty specific scenario and it probably wouldn't be best to spec that way considering it's not that huge of a gain.
The best thing about this change is it makes it less likely that high latency rogues will want to kill themselves. This change was really only made for humanitarian purposes.
Hemo will still be behind (marginally imo), but I'd say it comes out ahead for high latency players.
And the reason I bring up that rupture refresh talent for hemo, and not for backstab, is because you can't really manage to keep that rupture going with a backstab spec, unless you never use kidney shot. Hemo gives you plenty of combo points to do it.