Well, hot cable move between adapters is supported as of 8.2.1; see kb2023388. The catch is "between adapters". Not between shelf and adapter 🙂 I think this is one of those twilight zones where you do not get direct answers.
That looks dicey. But I suspect odds of success would improve if you did a takeover/giveback between step 1 and step 2 so each node gets to boot in a dual stack single path ha config. Interesting lab experiment, but wouldn't try it on a production filer. If you do try it, tell us if it panics on you.