I think you have the names mixed up. There is the Korg Electribe ES1 and ER1. The ESMkII, I'm guessing, is an upgraded version of the ES1 and the ERMkII of the ER1. I can't tell you much about the difference between the two versions of these, however I can say the ESmkII is sample based, so you should get some good samples if you want anything to sound good. The ERmkII, the one I have, is an analogue drum machine, you create the sounds, rather than edit the ones you have. You don't have to worry how good the samples you're using are. I chose to use hardware over software as I'd rather hear exactly what I'm changing. The samples you'd have heard do sound crap, but there are some good presets and you can make some good sounds on it. I read he uses the ER1 (not mkII) live and has on the new album (AONO I think). The ERmkII can be used for a lot of different dance styles - happy hardcore, techno, IDM.