Thank you very much, Dodain47!
I can point to the performance for another game, Digimon World 1 (NTSC-US). I played it a lot, and in fact I was able to recruit every single creature to the city using WiiSXR. The frame-rate holds quite well to the original game, and I found it to be pretty playable all around, to the point of playing it almost twice.
But is not perfect: I had a couple of random crashes (when entering one of the fishing areas near the mine, or when talking to a tree monster in the foggy forest area). Fortunately, it's not an "always crashes here" type of deal, pretty much every other time I went there or talked to that character it went fine. I would say that I got three crashes overall throughout my playthrough of 30/40 hours, so it's not that bad (although I recommend doing a save state each x amount of time just in cause when near those places). That said I don't know for certain if this is an emulator problem, or the game itself (as it can be reaaaally glitchy, there's even guides with all of them!).
Besides that, sometimes my Classic Controller would "freeze" for a few seconds. That didn't happen in the original game as far as I know, and it has happened only in this game using WiiSXR. I tried other games like Breath of Fire III, Grandia or Symphony of the Night, and it's the only one to show this issue.
I found the behaviour of this issue quite interesting. If you're pushing a button or moving in one direction when this freeze happens, it would get stuck for the duration of that freeze, and it always had the same duration of a few seconds, like clockwork. Because of the type of game it is, I found myself enduring it as otherwise the game functioned normally.
I'd say that if the control issue is something that could be fixed (I have no idea of how hard could it be), it would be perfectly playable.
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About saving, I only can add that, at least using WiiSXR, automatic saving has been working fine for me on the few games I tried. What I REALLY recommend is that you go to the emulator menu from time to time so your save file can be updated. Whenever you go back from the game to the menu, and it detects the ingame save has been changed, the emulator will flash a quick "Save File Updated" type of message.
If you save ingame and you push the turn off button of your Wii while still in the game, your Save File won't really be updated to contain the last changes (meaning your last ingame save). This happened to me the first time playing Digimon World and I felt incredibly stupid.
Also, if you use savestates, and then try to do an ingame save, and go to the emulator menu, you'll probably see an "saving error" windows popping up. I was worried at first, but at least on DW1 it saved correctly, and I read somewhere that the error message is just a bug.