So I've had a bit of hands-on time with my Logitech G13 keypad, and I'm not particularly happy with it, truth be told.
It works well enough; the software (as with all logitech's peripherals) is stellar.
The problems are, well, ergonomics. The keypad isn't actually all that handy - the 'hump' for your palm is too low, and a bit too close to the keys - so even in the supposed position, your fingers will be quite bent in the "rest" position (think as with a claw-grip mouse). The thumbstick is a particularly nasty thing, though - it's not in a good place, it doesn't seem to be 100% aligned as you'd expect (it seems slightly skewed anti-clockwise by about 10-15 degrees) and isn't exactly precise (afaik, 255 positional states per axis). The wasd keys have depressions so that you could locate them easier, but those depressions are rather faint. Worst of all, though, is the lack of a key row *above* the qwe... line - so where you'd usually have the number keys - which are fairly important in many games - here you need to rebind those somewhere else.
So, er, yeah. I'm not particularly impressed, it really just seems more like a small gaming-grade keyboard, and not a speciality device (like a mouse or a joystick). Maybe I should have gone with Razer's keypads, those at least look more non-keyboardy..
Edit: While I'm griping - I'm not sure if I like the t.16000m joystick - It works well, aye, but after just 20-30 minutes of play, basically my arm (wrist) starts to ache. Is that an adaptation thing, or am I stressing the joint too much? I've never had this stuff with a mouse (still don't), and I'm pretty sure I don't have an RSI or similar issue...