I'm still using an old 1B (512MB version) for Kodi, almost on a daily basis. Playing back stuff from an NFS share. I'm limited to 1080p but that's still fine with me, I'd need a TV upgrade first anyways.
It's showing its age though, and I had to hack up some stuff to use it properly:
I'm controlling Kodi via Yatse (Android app), and mostly just use the file mode to browse Movies and TV shows. I have them sorted and named properly anyways so that's not that much of an inconvenience to me. Using the fancy views that show artwork and IMDB metadata is still working but a little to slow.
But even in plain "file mode" Yatse was a little to slow and sometimes timing out when listing directories with 200+ items. This is where the hacky stuff comes to play: I built a simple proxy that intercepts the requests from Yatse and modifies them, namely, when Yatse is listing a directory it sets some field in the JSON that says "media type video" for example, when browsing for videos (forgot what the key is called exactly; currently at work). So I simply strip that key entirely from the request, and now listings take 1-2 seconds for large directories.
While I was at it I also started to intercept links to youtube videos and instead call youtube-dl to download them first and then have Kodi play them back via NFS. This way I get 1080p instead of just 720p and also have a history of everything I watched on YouTube, in case I can't find it anymore, or it gets deleted etc. It's pretty brittle since it doesn't properly track state or prevent you from triggering a second download while the first one is still active, also if you request a 50min video it will take a while until playback actually starts, since it needs to download it fully first. But at least it recognizes if a video has already been downloaded and just starts playback instantly. Turning this into a proper project is on my TODO list, but that list is mighty long.