New Pass Labs X.5 series versus previous X series

Pass Labs is in the process of re-dedesigning their entire X series into the new X.5 series. As of this writing X150.5, X250.5 and possibly X350.5 are already shipping. The X600.5 are expected to start shipping early in the new year. This thread is to discuss experiences with the new amps, their sound signature, perceivable improvements over the old series, and of course dissenting opinions. Everyone's perspective is welcome--X and X.5 owners, X.5 window shoppers, Dealers, and all other audiogoners with a passion for affect by the bug of audiophilia.
hocklin, have you considered calling Pass Labs directly? Folks at Pass are extremely helpful. Try:

Pass Laboratories,
PO 219,
Foresthill, CA
95631 -
Voice: 530. 367. 3690 -
Fax: 530. 367. 2193 -
www. passlabs. com

have a chat with Kent and let us know what you hear.
Peter is no longer with Pass Labs.
I've listened to both the Pass 600.5 and the 350.5 for a good amount of time on each. I ended up with the 350.5 as they fit my budget and space constraints. They are both very robust in thier presence. You can really tell the difference between the two as the 600.5 really had alot of power all accross the spectrum and would probably drive the hell out of some good line source peakers. At 155lbs each they were formidable giants in my living room when I auditioned them for a month. But when it came down too it I got a great deal on the the 350.5's and the fit nicer into my salamander rack. As far as a loss in performance between the two I would say that the the 350.5's are are about 15-20 % less in performance than the 600.5's. They still bring a smile to face when I think about them and if I do a major remodel to my place I will definately make more room for larger amplifiers, just in case I score really sweet deal like I did on the 350.5's in the future. OOps almost forgot to mention that previously I had owned the 100watt Aleph O's and the X.0 pre-amp. also Martin Logan Statements.
Magichandslarry, did you perceive any other difference between X350.5 and X600.5 except for power? Please elaborate. What is the rest of your system? What music do you listen to? 

Hi, I'm wondering the real differences between the x600 vs the x600.5. With quite a bit of price difference, can anyone tell me if the x600.5 is worth the extra $$$. Thanks all.