I could see the choking thing going very bad the first time you tried it if the girl didn't like it. I'm close to getting engaged and we've done pretty much everything but that, and getting tied up. She's a "nice girl", but that hasn't stopped her from enjoying buttsecks fairly often. But choking? That might be hard to explain if she asked what the heck I was trying to do.
Maybe I can try it from behind first and just extend my fingers around towards the front more, then if if anything goes 'weird' I can just say I was massaging her neck.