11 hours ago, desertfish said:
Which option would you choose and why?
Make it work how YOU want it to work. Each of your options has some headaches (for you and for users) but since the major changes in R39 (banking, rom routines that live somewhere else) are probably important for your software, bottom line is you have to decide how much dev time you want to spend targeting an emulator version (and maintaining a parallel code-path for it) to service an emulator/rom version that we know will not be what comes out as the X16 hardware or any future official emulator release.
Its true that there's a bit of a disconnect right now, with the 'docs' all being r39 but the official downloadable emulator release at r38, but I suspect behind the scenes there are goings on that probably represent a good reason there hasn't been an official r39 release as yet. If you target r39 then even if they make some tweaks (whether as part of a release or due to feedback when they ship hardware for beta testing) you can adapt and roll with it. If you target r38, then you know you're developing toward a dead-end and will have to retool for r39 eventually anyway.
It seems to me that anyone with the chops to use this particular piece of software (which probably doesn't include me at present although I hope to have the time to play with it later this summer) will be able to make or get their hands on an R39 build during the time (which may be shorter or longer, who knows) before an official r39 release.