Hehe yeah the UFO8 claimed to work with all enhancement chips, but it turned out that to for example run Yoshi's Island, you need to put in a cart of Yoshi's Island in the top... completely defeating the purpose. Perhaps the idea is that you could use one SuperFX game to run another one, but that doesn't seem to work either from what I read.
I recently bought the SD2SNES as I mentioned a while back, and it is indeed fantastic. But as BocoDragon said, if you're only interested in translated Japanese games the Powerpak should probably be enough. Do note however that you will need to desolder the DSP chip from an original game that uses one, like Super Mario Kart, to put in the PowerPak, basically destroying the original game. I'm not sure how many games use the DSP chips but it seems to be the most commonly used enhancement chip.
Another "problem" with the Powerpaks for both the NES and SNES is that it seems they're not being worked on anymore. That is, there hasn't been any updates for them in years. And they're not open source so no one can take over development. But they already work well enough.