Who Does the Best Mods on CD Players

I own a Pioneer PD-75 player. Am considering spending a couple hundred or so on a mod since I can't afford to buy the player of my dreams. Any opinions about who out there does the best job modding players - for example John Hillig of Musical Concepts or Stan Warren, etc.? Are these mods worth the money? Do they really improve the sound of the player? Any advice is very much appreciated.

Rockyboy