Martin Logan CLS "Buyer's Guide" Question

I’ve wanted a set of Logan CLS’s since I first heard them back in the 1980’s and would like to start looking for a pair, but could use some help to know for sure that I’d be buying a good set. Would you guys please opine on these concerns?

- What do I look for in a decent set to avoid a ’lemon’?
- What is the difference in characteristics between ’generations’ of CLS (I, Ia, II, IIa, IIz...)
- How can I identify which generation of CLS I’m dealing with, and how important is it?
- Would there be any concern about age of panels, or if the panels are replacements?
- Would you recommend a different model of ML speaker, and if so - which one, and why?

My current equipment is:
McIntosh C28 (presently in use)
Krell KRC-3 (inbound...)
Bryston 4BST
Dahlquist DQ10
Polk PSW650

I hope to replace the DQ10s in favor of the Logan’s, but it’s helpful to know what I’m getting into beforehand, to avoid a costly mistake.

Thanks in advance!