My only experience of boutique derailleurs was a Pauls set up that came fitted to a second hand Manitou FS that I bought. The fitted combo of XC Pro thumbies and Pauls mechs was clunky and inaccurate. I replaced them with STX RC rapid fires and mechs (all I had kicking around at the time) and it worked ten times better. Hand crafted anodised bits look very pretty, but in my experience, don't work as well as mass produced cheap Shimano.
1991 Trek 7000, 1990 Marin Muirwood, 2012 Charge Duster. 1997 Cindercone.https://www.facebook.com/groups/456208327901609/