Personally, I’d wait for OH3 for your production environment. I don’t know when that will be, but there’s going to be enough new stuff that you can treat it as “brand new”.
In the meantime, I think the most valuable thing would be to use your OH2 setup to learn about next-gen rules using Jython. Those will definitely carry over to OH3, and by all accounts are vastly superior to the old rules.
I had hoped to start learning Jython this summer, but my job has kept me far too busy to play around with it. However, Rich and others have started posting Jython rules to stock the community with examples.