They all do the same job mate, the only thing you may find on some is they have a fuse inbuilt, but I have used Suzi,kwak relay's off GS,gsx,gsxr and off z on ever my GS the kat and lots of previous bikes.
Main thing is some have a earth wire plus the starter butten, some just have a stater butten and you earth it to the frame or run a earth wire to one of the bolt holes.