I have had a pair of ES Lab EX-1a in my hands for a couple of days: I pinged Benson a while ago to inquire about a potential European loaner tour, and ended up buying a pair. It's too early to form a definite impression but so far they are exceeding my expectations, with very nice tuning and gobs of details.
These might be the best price/performance electrostatic currently available. They are in a completely different class versus the Stax SR-X1 (which I had and disliked), and L300/L500 (which I also have).