I have the earlier (3rd generation 4 ohm) SRS2's and they are incredible. I have not re-capped them yet and they still amaze me. Since the 2.3’s are probably equal to or better than the similar SRS2's, I don't think you will be disappointed. Of course, as always a lot depends on the condition and prior care of the speaker
It's not just the soundstage they create, they way they reproduce music is realistic and very pleasurable. I'm not really a "Polk guy", this is the only vintage Polk I have ever heard so Mystery is much more knowledgeable as far as comparisons than I am. FWIW, there must be a reason that only some of the SDA's were Signature Reference Series. I've never heard the 2A's but I think it's safe to say that based on specs and the fact that the 2A's are not SRS's the 2.3's will probably be a noticeable improvement if you have the room for them.
The 2.3's are easier to drive (6 ohm) than mine but clean power and proper set-up are still critical. I think the SRS2's & 2.3's are the "Goldilocks" of the SRS line. Not too big, not too small. I have mine in a 12 x20 room and they sound great. In a smaller room it was a different story, the midrange was off.
Good luck & enjoy.