The Kodi developers just recently released their second release candidate for the next major version: 16, code-name Jarvis. I decided to upgrade my installation today, largely in the hope that it might fix a few annoyances I've noticed in version 15.
my MythTV server, usually once or twice a week. I can't remember Kodi ever crashing outside of watching a MythTV recording, so I'm pretty sure it's something specific to that particular function. I've also seen some strange video behavior while watching Crunchyroll video streams, where the video will slow down and the audio will skip. That only lasts a few seconds, but it's certainly annoying.
Neither of those are major problems, so I wasn't willing to upgrade to version 16 while it was still in beta. Now that it's progressed to a second release candidate, I think it's likely that it will be stable, and unlikely to introduce new problems. I can't be sure it will fix the old ones, of course - only way to find out is to try. I'm hopeful, though: both the video playback on Android and the Kodi PVR interface have changes in Jarvis.
The basic installation went smoothly enough. I decided to completely wipe out my old Kodi install on my Fire TV and re-install the new version, rather than attempting an upgrade. Adds a few extra steps, such as reconfiguring the MythTV addon, but I think it's worth the hassle to avoid any problems related to old left-over files and settings. Only took about a half hour to download the new version, install it via ADBFire on the Fire TV, and configure the various settings and addons that I use.
Then came the difficult part - getting my custom version of the Trakt.tv addon to work properly with MythTV and Crunchyroll. I actually didn't need to do anything to the Crunchyroll part, as nothing had changed in version 16. But with the MythTV PVR addon, there are changes to way that Kodi provides information on which recording is being played. I spent a couple of hours debugging and modifying my fork of the addon code to adjust. It's still not a great hack, relying too much on the specific MythTV addon formatting and using the Trakt.tv episode text search function. But it works, which is good enough for now.
So now I'm up to date with the latest Kodi version. Over the next few days and weeks, I'll see if the issues I had in version 15 are fixed. With luck, version 16 won't have introduced any new ones!