Not surprising that John would say his current modes were the best. ;^)
I owned a pair of Duntech Princess for 19 years, by far the longest for any speakers I've owned. In addition I had three good friends who owned the same model but each of us had different rooms and configurations. So I had a pretty good feeling for their performance.
Over that time I heard various DAL models, including the SC IV/IVa which was the closest sibling model, at a local dealer and a number of times in the DAL room at the Las Vega CES where John himself set them up.
In my opinion the DAL models were very good, but lacked some of the refinement of the Duntechs. There was just a better sense of musical realism in the Duntechs.
I believe there are at least two reasons for this. John was concerned with costs and used less expensive drivers in the DAL models. He also reduced construction costs by having straight front edges on the cabinet sides, rather than cut back to match the stepped back baffles for the drivers. Yes he continued to use heavy felt surrounds but I think the dispersion and sense of openness was greater with the Duntech cabinets.