After 12 years with 3.6´s I switched to 3.7´s when they came out. I feel that the 3.6´s had more, slightly rounder bass but not as articulate as the 3.7´s. The 3.6´s could sound a bit weightier but also somewhat bloated in comparison. Makes me wonder why they released the DWM´s.........
Better integration in 3.7 and I have not noticed anything about the depth, openess or the bloated midrange you mention. I have not heard the i-model with the tape behind the midrange (no tape on the 3.7)