The aim assist you're experiencing is coming from the weapon, not Ambush. Ambush does give you great stability, though. I use both Shortgaze and Ambush. The one I found to be very underrated is Hawkeye, especially for a bigger map. It's a mid-zoom scope, but it's damn good at what it does. I only tried that one out recently just to compare it to the popular scopes, and to my surprise it was quite sticky and accurate.

The ambush scope has one of the lowest Im assist. If you want aim assist use shortgaze

Idk. I hadn't ever used it in the crucible till last week and the hit box seems enormous compared to preadyths