I like the SE215's, the sound is good, the external sound isolation is decent if you use the foam tips. I still haven't really settled on which size to use but I always have trouble with anything in ear be it plugs or ear phones. I find it pretty hard to insert them, but maybe I'll get used to that over time. It does start to hurt a bit in one ear after wearing it for a bit longer but like I said, my ears are pretty difficult.
One thing I don't like about it is that there is sometimes a high pitched whine, specifically when I turn on bluetooth on the drum module. Once I start playing I can't hear it anymore, but it's very noticable if there is no other sound.
I also had to buy an extension cable because the cable is a bit short and I wanted some more freedom (to pick up the sticks I kept dropping...).
Overall I'm very happy with them though, it's great to be able to hear the sounds of the e-kit more than me whacking the pads.