I just received some MD Tributes which are considered an upgrade.  I also have ER4ps but I dont use them since one ear has shorted out.  You should list your music preferences so we can help us out.  Also what did you think of the UM2s which would help us give you a better opinion.

Good choice on the detachable cable.  Make sure you buy it from an authorized reseller since some of the amazon ones arent.  I am currently getting mine reshelled through Fisher Hearing.  I read an interesting review of someone who tried as closely as possible to get them like the es3x.  Just...