E3 card reader gives you best of both worlds, you can use their own firmwares, or just drop any already PSGroov complied hex in if you can't wait for updates, or you want to test your own changes out.

Big news from e3 card reader PS3 team that release free e3downgrade firmware !
support downgrade 3.5/3.42 to any firmware, just enjoy it ! (12.04.2010)

E3 Card Reader Micro SD/TF Card Reader PS3 Dongle with 128KB Flash Features
http://www.e3card-china.com/index.html

youtube: E3 Card Reader 3.42, 3.50 and above Downgrade for PlayStation 3

http://www.youtube.com/watch?v=wi6s-W2gXKU

Brand New E3 Card Reader Micro SD/TF Card Reader PS3 Dongle with 128KB Flash

1: 32bit processor with 128K flash， has strong processing rate and high expand space.
2: MicroSD SDHC supported, can load software and game from it .
3: Multi-System supported, include WinXP/Vista/Win7/Mac OS/Linux, this means you can upgrade and use e3 card reader in most system.
4: 4M FLASH onboard, so you can save any ps3 software very conveniences, for example, you can copy any backup manager easier.
5: Super-Drag-Plug upgrade mode,just copy BIN file and paste into e3 card, 1 second fininsh upgrading, no need any extra upgrader.
6: dual firmware booting mode, this means hermes v4b and kakaroto latest firmware integrated into one code, and you can use any of them by yourself , no need re-flash code.
7: Support any free PSGROOVE like hermes&kakaroto.
8: e3 card reader has CE, FCC and RoHS certification , it is more safer and environmental product, and with 2 year warrant