Dunlavy SC-IV vs Duntech Princess

John Dunlavy himself said that DAL speakers were better than Duntech he designed.

""And no! The speakers I designed in Australia did not exhibit the level of accuracy of our present designs because I had neither a decent, large anechoic chamber or the measurement capabilities available with the MLSSA system, time-domain spectrometry, and other gear we presently use." 

John could have used any drivers and components he wanted. He had companies pestering him and sending him drivers all the time; and he could pick anything he wanted. He was a practical man, no need to use an exotic $400 tweeter when he got excellent results with a $40 tweeter. 

Due to his 1st-order designs the drivers he used had to perform well over a wide frequency range. If you read his whitepaper Cones, Planars & Domes - A white paper on the performance attributes of various loudspeaker designs you'll have a better understanding of why he picked conventional cone drivers instead of those made with exotic materials: the exotic cones store energy.. Also be sure to read the Stereophile interview John Dunlavy: By The Numbers. 

I don't see how the Duntechs could have been more refined considering he didn't have the large anechoic chambers at Duntech, or the advanced measuring equipment that he had later on at DAL.