Thanks for the review and details of oddities. I'm also planning on diving with the watch in April with an old Mares puck as backup. This particular oddity seems really annoying. I was just reading Oceanic's FAQs and they claim that's not what the behavior should be... I wonder if it was something they fixed recently?:
Once you reach three feet from the surface, Oceanic+ will show you a prompt asking if you are finished with your dive and the app will automatically begin a 3-minute countdown. You can press the action button to end the dive which activates surface mode. Or if you are not done diving, you can begin a descent and the app will switch back to dive mode.
Perhaps they have fixed that oddity in a recent release. It didn't behave that way when I dove with it. There was no prompt on reaching the surface. One good thing about the app is that you can make the prompts difficult to miss with the flashing screen, sound and hepatics. If there was a "nearing the surface" prompt, I wouldn't have missed it.