I've used the EBC Greenstuff pads before - I got 7000km out of them (by comparison, the replacement Ferodo pads had 35000km on them when I wrote the car off). The GreenStuff pads made more brake dust than normal pads, but it was easier to clean off.
I found the GS had more initial "bite", but the actual braking distances seemed no better - and they chewed discs.