Thiel 2.3 vs 2.4 the real difference

I've owned many Thiels including 2.3's, and my good friend owns 2.4's. I think Swklein nailed it in his comment; the 2.4, to my ear, retains the best attributes of Thiels while being a lot more willing to sound musical with a wider variety of gear and source material. So I think there is no question that it's an upgrade, but, the question is how much of an upgrade and what would it cost you. I would personally pay the difference between used 2.4's and used 2.3's in order to have 2.4's. By the way another interesting alternative is 1.6 with a used REL Strata III sub : - )
Art

My Thiel 2.3's were early model, and I know that there was one major change early in the life of that model: an upgrade to the midrange driver that was reputed to smooth out the upper midrange. I can't say for certain that I ever heard a 2.3 with that upgrade.

So, the difference between 2.3 and 2.4 MAY depend substantially on whether the 2.3 has the newer midrange driver.

Art

In my own personal experience, side by side testing is sometimes not revealing of differences, unless you have first spent quite a bit of time listening to each of them on it's own. I don't know why. I assume it's because your ear somehow learns the character of each of the different speakers. It sounds like you have done that though.
Art