Anyone have any info do these work?

Was planning on buying few of both as Hori Game Boy Player pads are hard to come by.
I've had both for sale as Retrozone sells them. They're both excellent. The NES is a little difficult to get an NES controller in there, but it works great with all models of the NES controller. Keep in mind that the Select button is mapped to Gamecube's Z buttons, so you will never have access to the Gameboy's Select button in any game you play on it. Using an NES controller to play Gameboy games through feels great and natural.
The SNES is where it's at for fighting games like Soul Calibur 2, retro games or playing GBA games. Same limitation as the NES though; Select is actually Z.
Off the top of my head heres a few Gamecube games that greatly benefit from the SNES pad:
Soul Calibur II
Capcom Vs SNK 2 EO
Megaman Network Transmission
Megaman X Collection
Alien Hominod
Zelda Collection
Sonic Mega Collection
Resident Evil
Resident Evil 2
Resident Evil 3
Namco Museum
Both adapters have no lag and are really quality items. I highly recommend both. They also work with any Wii games that support Gamecube controllers AND allow digital control. Some that do include the Ulatime Shooting Collection Shikigami no Shiro 3, Meramasa and obviously, most VC games.