I have a Stan Warren modified Pioneer. Well worth the money spent IMO (in my opinion). Never had a problem with it. It seems these things usually break right away, so if you have a good history with yours already, you are hopefully safe. Stan gives a warranty on his mods. Stan does not warranty the stuff he does not mod like the laser assembly and transport, etc. He related to me that although in theory the warranty is voided, he knows of authorized techs who have fixed various things under warranty he has modded over the years. The manufacturer has to rely on the tech, if the tech does the repair. If it is still under the warranty period the tech gets paid by Pioneer for the repair. Only he (and you) know it has been modified. If he won't repair it under warranty you just walk away and he does not make any money. There is of course still some risk I guess. But even at double the cost the Pioneer is still a great deal the way it performs after it has been modded.
The modified player is better accross the board in the areas you mention IMO. It is also more "analog" sounding.