I've owned both of the retro models and really dug both. It's been a couple of years, but I preferred the J-retro to the P variant. I couldn't tell you why. I just remember the J-Retro worked very well w/ the set of Bartolini PUPs I ran with it. I had the P variant paired with an Aero pickup. I liked, but didn't love that pairing. Never tried the P variant w/ any other PUPs so YMMV.
John's involvement on the ACG filter pre is what swayed me in that direction for my current build. Also, both John and Alan were very responsive when I've emailed them in the past.
Adrian at Nordstrand was also great with email and communication. The only real disappointment in the CS department I had was with Audere. No one would answer my emails. That, coupled with some answers I received from others back in pt. 3 of this club made me veer away from them. Cliff's input and Adrian's communication led to Nordstrand winning my business for my first CB.