I've just got the Mediaremote (from Mutilator on the digital-car.co.uk forums); I haven't used the ATI remote, but this seems to work quite well. Here are a few comments after testing it out for a week or so....
It doesn't have a mouse-type control - it is purely digital, on-off, button based.
It has quite an array of buttons - I've got almost every audio function of Frodoplayer mapped to a single button, without the need for any combo's.
It's a handy size; not too big, but not too small that you end up pressing more than one button at the same time.
The buttons would look great if someone modified them to be illuminated (they are semi transparent).
I have used it up to ~2 metres away and it seems to work fine.
It is RF, and not IR, based; so doesn't require line of sight.
I just installed the driver from
www.mediaremote.com, and Girder (it uses the same ATI plugin), and mapped the buttons to normal keyboard presses and then changed the keymap in Frodoplayer. Works great.