The tonal balance is quite different between the 2.3 and 2.4. The 2.3 still has the older Thiel hyper-analytical sound; the 2.4 retains the best aspects of that sound but leavens in a degree of warmth missing from older Thiels. Certainly worth a listen in person-- if going back to Thiels (I had CS2s for 16 years before moving to Vandersteens) I would definitely choose the 2.4s: they're a kind of middle ground between the older Thiel sound and the newer Vandersteen sound (perhaps a third of the way over towards Vandy warmth).
