I don't know the Berkeley, but I agree with those saying the PWD is a good sounding DAC (the MKII is considerably better than the I). I'm in the group that has experienced better sound using a preamp instead of the volume control.
Two potential reasons for hesitation for the PWD:
MSRP on the PWD seems to be frequently undercut, which contributes to what looks like a fairly weak resale market. Of course, if you get the savings on the buy in, it won't matter.
As all the discussion on the boards seems to indicate, the PWD is a work in progress, particularly on the software side. If you are using a computer as a front end, you may experience hassles in implementation. If you do (as I did), and cannot sort it out yourself, PSA, which is an audio firm and not a software firm, may not have the know how (or inclination) to help you sort it out (in my case,they didn't for me). Of course, there is a general issue about the kludgy mating of computers and DACs, but it might be cause for hesitation with PSA.
Best,
John