I made similar queries about earlier drivers. Sean Casey has so far discouraged updating Druid 4-08 with any of the newer Zu FRDs, beginning with the 2010 HO driver. One problem is that Druid to-date did not have a full Griewe implementation. The Griewe scheme does affect the FRD's performance well into the midrange. He has also said in the past that the Druid super tweeter won't mate well with the newer FRDs. Superfly does have a full Griewe implementation, and its super tweeter has enough output to sound in balance with the "hotter" FRDs that have emerged in the line since the 2010 HO.
I wanted to update my Druids to the HO or nano FRD while waiting for Druid V, so pressed Sean In 2010, 2011 and again early this year. He at the time said he viewed Druid 4-08 as a finished design that took the circa 2000 Druid design as far as it could go without starting over. Essence, Superfly and even in some respects Omen, were ventures beyond original Druid and now, what was learned there plus trickle-down from Dominance and Def4 will inform the next Druid, completely remade.
Phil
I wanted to update my Druids to the HO or nano FRD while waiting for Druid V, so pressed Sean In 2010, 2011 and again early this year. He at the time said he viewed Druid 4-08 as a finished design that took the circa 2000 Druid design as far as it could go without starting over. Essence, Superfly and even in some respects Omen, were ventures beyond original Druid and now, what was learned there plus trickle-down from Dominance and Def4 will inform the next Druid, completely remade.
Phil