I posted this in a different topic:
The newer "Reference" series replaced the Synergy series, and the "Reference Premiere" series replaces the outgoing "Reference II" line. The RF-7ii has not been replaced yet.
Klipsch made it extremely confusing to compare used models to current ones, but basically just follow the driver materials to see what tier a series sits in.
Example, following the 8" woofer models
Titanium tweeters and Cerametallic woofers:
Reference(1st gen, RF-3)
Reference(2nd gen, RF-3ii)
Reference(3rd gen, RF-35)
Reference(4th gen, RF-82)
Reference II(5th gen, RF-82ii)
Reference Premiere(6th gen, RP-280f)
Aluminum tweeters and IMG woofers:
Synergy(1st gen, KSF 10.5)
Synergy(2nd gen, SF-3)
Synergy(3rd gen, F-3)
Synergy(4th gen, F-30)
Icon(5th gen, KF-28)
Reference(6th gen, R-28f)
Then I would consider the larger Titanium tweeter models to be on a high performance tier, as follows:
RF-7(1st&2nd gen)
RB-75(3rd gen)
RF-83(4th gen)
RF-7ii(5th gen)
????(6th gen)