Lot of peeps like the SD-E. I never tried the SD-E but have had others and when shooting the differences b/w them are subtle IMO. I've never tried the flat face triggers though.
So my day job is training/curriculum development and I met a girl who developed this curriculum for the Army. It's pretty good info.
@EugenFJR fjr do you use this too?
http://armypubs.army.mil/doctrine/DR_pubs/dr_a/pdf/fm3_22x9.pdf
That's what I thought too but really integral suppressors are easier. The sleeve slides off and its just a long monocore.
Or did you mean the gun itself?