Interesting. I was unaware of any fundamental differences between the preamps. A Millennium 5 passed through my collection and I did notice that it sounded brighter than my Cirrus basses but it had a maple fingerboard and I attributed the difference in tone to the fingerboard.
I have a Millennium 4 with J/J pu's on the way to me. I should have it Thursday. I typically do not get thrilled with J/MM pu's...have had Lakland and Roscoe with those pu's. I am curious to see how the J/J sounds.
I greatly enjoy sharing experiences and insights about Peavey basses here but my collection has now increased to 7 counting the Millennium that is on the way. My favorites are my Cirrus basses and I play them frequently, however, if I have gig where I worry about the possibility of damage I just take my Foundation 5 which already has some dings in it. I paid $199 for that Foundation and it is a killer bass that came to me needing EVERYTHING adjusted. Whoever had it was probably glad to see it go because it was terrible to play. Now it is a dream to play and looks great on stage.