Debian upgrade

I've done some experimenting with trying to bring the box up to Stretch. Here's what I've found:

• The NG Apache build includes a couple of custom or optional modules that aren't shipped in mainline Debian currently (mod_privsep and mod_authn_privsep), which will cause it to fail to start.  I've not investigated further as to whether the functionality is now a core part of Apache or in another module, but either way that will need investigation.
• I use Exim to ship mail, both for readynasd to use as a mail relay and for general local delivery - it uses another machine on the local network as a "smart host" which actually sends it out to the world.  After upgrading as many of the dependencies as I could find, the queue runner segfaults when trying to deliver mail to the smart host - in particular it's SEGV_MAPERR which suggests that there's still a library somewhere it's having trouble with, which I couldn't identify.
• Once a whole bunch of core libraries have been upgraded, readynasd itself will segfault also because of a library incompatibility, which entirely kills the UI and may prevent the unit from booting in the first place.
• I was able to revert to stock firmware using OS Reinstall in the boot menu, but this then left the dpkg status database hosed, which required restoring from /var/backups and reinstalling a bunch of packages to make the filesystem actually reflect the older database.

Since it seems the product line is EOL'd and the software apparently abandoned, it seems like it's going to be a lot of effort to continue maintaining what for me is now a 6 year old device, and I suspect that replacing it wholesale may be a better option.