I find mine seems to pull out of the torque dip sooner and harder on petro 94 than shell 91, but I haven't logged it to see if it's all in my head or not. I typically only run 94 when I know I'll be beating on it a lot, I get noticeably better mileage on shell 91.
I have to finish rescaling my MAF and flash that tune before I start looking at any knock on 91, when I get to that I'll try to get comparable logs between 91 and 94 to see if/where it makes more power and where it might be knocking.