The difference about $500!
Seriously, they almost spec out identically & have most of the same features between them, the 260 is accesible via computer control also but other than that, not much difference really.
Can't really say, have only used the PA personally.
There is a new PX out as well that is speciafically geared for powered speakers & has many of the brands built into memory for configuration.
http://www.zzounds.com/item--DBXDRPX