Kentaree,
No, I hadn't seen it, but at that price it's pretty much guarenteed to fail. In my experience, Datel haven't had a good rep (never tried it for myself, so I'm biased, but I've heard some bad things).
At any rate, that's a slot-1 device, which means I could not play GBA homebrew on it at all, which is a large concern for me as there are some really nice GBA homebrew games out and about!
Nex, yeah, I'm sorta regretting getting an EFA-II since it doesn't natively support booting .ds.gba files (like the EFA-I does), so I need a little workaround which requires me to be near a PC.
I don't have a pass-through device since I used WiFiMe and my flash cart to flash my firmware.
A popular slot-1 device is the M3 which seems to be quite a good device.
Natrium42 lists a few of the more popular devices, but then again, each one performs differently, and each person may need it for different purposes (eg DLDI support, .gba support, .gba with 32MB RAM support, etc, etc).