Comparing Orion to Safari, it feels like there's a couple of differences in how this gesture works, which make Safari feel slightly "better":
Safari seems to be a bit more tolerant of slight vertical movement before a more dominant horizontal swipe. Especially when trying to do the "forward" (right to left) gesture (at least for me - likely due to hand positioning on trackpad). A little bit of vertical movement inhibits the horizontal swipe.
The ratio of trackpad distance covered, versus swipe effect on the screen, appears to sometimes differ quite significantly. I have to swipe "further" on Orion than Safari. This may be correlated with the above issue, and it's hard to reproduce precisely. It looks to me like the swipe is based on "speed", not just "distance" swiped. This may work, but I also wonder if it would be better to incorporate a little more difference so the screen effect matches more of the user's finger movements, so they can "check" what they are swiping to, then proceed if that's what they wanted to do. If you are 'peeking' to check, you'll do the gesture slower, meaning you end up having to pull a lot further to see and proceed.