I've had an ER4P for over 8 years now, and I have never regretted the purchase. I most recently tried the Beyerdynamic DT-1350, but it sounded reletively dark and had nowhere near the clarity of the ER4P especially in fast string passages (I listen to a lot of symphonic music). Currently, I am pairing my ER's with the TTVJ Slim portable amp and this combination adds a bit of tube like warmth. Using the Channel D Pure Music player on my MacBook Pro yields a similar result. Because I do not hear bass well, I slightly prefer the ER4P to the ER4S (I have the 75 OHM modification cord).
However, I do enjoy listening to classic pop (eg Simon and Garfunkel) on the DT-1350 which lends a slight "caramel" character to tonal balance and where maximum resolution between instrumental choirs is less important.
(Home rig: Meridian 508.24, conrad-johnson premier 17-LS preamp, c-j premier 11a amp, Aerial Accoutic Model 6 speakers biwired with Nordost blue heaven cable).