not as smooth as an ultegra 6600, but no over shifting like this
pro
no extra spacer
triple compatible
12-36 cassette compatible
sram rear MTB derailleur type 1 is cheap, I've paid mine 25 $, brand new, old stock.
cons
downshifting more brutal than standard SHIMERGO except you get a 12/30 cassette
the key is special cable housing from Bottom braquet to sram RD.