I love the looks of the L-780, especially the metal grill and fine cabinetry. I had the II version also, and enjoyed them for a few months but agree that they aren't ADS's best model in that general size and configuration. They sounded quite pleasant, and I felt that they gave of their best for low level listening. I sold them for a modest profit because to my ear they sounded a bit thin in the mids with cello missing the "wood" and sax missing some bite. I found this true for both the I's and II's, and was slightly disappointed that this was the case in a 3-way ADS.
I could have lived with them, however. It isn't that I found them so fatally flawed; it's more due to my having been more highly impressed with several other ADS models in the past, and thus felt that they didn't represent the brand as well as they could have. Though they did most things quite well, they weren't a great match for my listening preferences is probably the fairest way to express it. If they match up well for yours then you may love them and find them as alluring aurally as they are visually.
I agree about them lacking some in the mids and a little in the highs, the bass is very strong though. I noticed they have a switch in the back under a little cover along with the fuses, I turned the highs up and they sound better.