I've done a comparative review of the two headphones in the title, both sub £100 headphones.
The Beyer's are not available any more, but I am a long time fan of these brilliant headphones witha stonking price / performance ratio.
The new Goldring DR150's have received some rave reviews so far, so I decided to buy some and put them up in a test against the DT531. Both are fairly similar priced headphones so the test is fair.
I've written the review primarily for headfi so I will just link you to it.
http://www6.head-fi.org/forums/showthread.php?t=194389