Good to see you back! I think the last I saw you was in 2019?? A lot has changed since then! You’ll definitely have a light and day difference using anything made this year. Possibly consider writing a new card from scratch, rather than trying to upgrade your current installation.
I’d be a little biased by saying that my custom DEOT image is the best OOB experience, but it is what I’ve tried to make it, ironing out kinks as users reported them, and keeping it up to date with official updates to the launcher. There are a lot of extra emulators setup, and existing emulators run fast; including SNES super FX emulation etc. I’ve mainly updated the Retroarch cores via buildbot, keep Retroarch updated, and have the underlying Debian OS updated.
I would release a new image each time I made changes, which was fairly frequently, as people reported things wrong, or I felt that something needed tweaking. I haven’t updated in a while; not because I’ve lost interest, but more because I’m finding less things to change.
With regards to gpsp, I’ve only had issues when using an overclocking, and that’s something that for gba, really doesn’t need to be utilised. It was some micro stuffers, and slight audio distortion. This possibly coincided with the flickering that some people experienced. I’ve provided a few different scripts to try and get it to behave the way you want.
For me, it runs exactly the way I expect it to on both a R16 and a R16-J 3.1 cpi board and a first Gen cpi board, but some still report things wrong with their installation. SD Cards are ridiculously cheap, so just try it out, and see how it feels.
What was wrong with your gpsp back in the day? I can double check it’s not something present in the DEOT image. If you do try it out, I’d be keen to see your feedback, as a founding Gameshell owner who went through the early Os renditions!