Conrad Johnson preamp: ET5, ET7 (series 1 or 2) or ET3SE ??

Have always been a CJ preamp fan, but never an owner.  Taking a serious look at them again.  Of the ET series, I have only heard the ET5, and that was some years ago.  So I started looking for a used ET5, and in the process finding 7, 3, and 3SE, making me expand my thinking.

i wonder if anyone has compared the five models?  As I understand it, the 5 was replaced by the 7, which was then updated to the 7 series 2.  Does it necessarily follow that the 7 is better than the 5, with the 7series 2 even better yet?  And looking at reviews, TAS loves the 3SE, so is it “almost” as good as the 5 or7?  I also know that the 3 is upgradable to the 3SE, and the 7 series 1 to the current 7 series 2, providing a couple additional paths to consider.  i should state that all are within my budget, so that while I don’t mind saving money with the 3SE, I have money for the 7 (used) in my audio budget.

I really wonder if someone has really compared any combination of the above, such that you could help me eliminate one or more of the possibilities, or help me focus on one or two units.

I know that it will be system dependent, so I am running Naim digital and Naim preamp into a Primaluna HP amp, driving Proac monitors in a near field set up.  I listen to mostly female vocalists, acoustic rock and acoustic jazz.  I love soundstage and bass is not important to me.

((not that I want the discussion to go sideways, but this kind of opens up the philosophical question of, given a specific company, are the new models better than the past year models, and the more expensive units better than those less expensive, and is an update/upgrade always an improvement.))

thanks for your thoughts,

Bill