I have only seen the Crius II for sale at one domestic online store. It seems to be available from all of the Chinese outlets we all use. I don't know why it hasn't been embraced by the vape shop owners in the US. I guess they have to devote so much room to the Smok products that come out daily.
The Crius II is for those "in the know."
If it doesn't become more popular, I might end up being very, very glad that I accidentally bought 6 of them. LOL
I can't compare AF on the OBS Nano and Crius II to the Zeus since mine isn't here yet. I do think the AF on the Crius to be better than the Engine Nano. The flavor is better too. I will certainly weigh back in when I have had the chance to give the Zeus a test run.