How does the ATT M1 head compare with the Feather AS-D2 head, in terms of build quality, aggressiveness, smoothness of shave, and other aspects you may find pertinent?
I don't have the Feather AS-D2 but the ATT M1 is a bit more "aggressive" than an EJ DE86/89. It's still a fairly mild razor though, so I hesitate to use the term "aggressive"
The build quality of the ATT is excellent rivaling Tradere, its rock solid.