The difference between the LCD2 and LCD3? About double the price
I did listen to the LCD2 and 3 at a show. I wasn't expecting so much of a difference but there it was. The soundstage was wider and there was more of a separation between instruments. This was with ALO's Reference 8 cables for both.
FWIW, I prefer the LCD2's use of wood for the cable connector. The metal clips on my LCD3 that join the wood cups to the cable connector has failed once and I had to send it back for repairs.
I like the LCDs for their ease of driving so I can even use it (on a pinch) with my iPhone headphone output tho it does deserve better.
I still prefer the HE6 if you have the amps to drive it. It is less dark than the LCD3/2