Everyone has a difference in opionions which is cool. I didn't like CCH aliens and given the soft lobes I won't like the Fixe version either. I just destroyed too many of them. Personally, my rack is 99% BD (and I am not sponsored to say that), and the C3's have allowed me to do things that were impossible without. When Mike and I went and did the first all gear ascent of Shangri-la (Mike did the crux pitch) the only reason that it could be done was C3's were narrow enough to fit
(Mike on the bolted 5.12d pitch tpotally on gear)
and here is the rack
Nothing else fits, metolius, aliens,.... they all are too wide. The metolius with the braze on the outside just takes up too much valuable real estate. Aliens are just too wide. Slider nuts while I use on leads of other routes in granite or basalt, I would not trust taking long falls on the soft sandstone due to the expansion range.
I am going to do a three pitch linkup next month which will require 12-14 of them (I joke if I can find a long enough rope since my longest is 100m, I'll do a 5 pitch linkup).
Personally, on another route while trying to work through the crux, I took multiple 30fter's onto green (0) BD C3's, three of them in the same day on the same piece, without any problem of durability. I've also taken whippers onto the purple (size 00) and the grey (000) and without saying also the red (1).
I will say Metolius tri-cams and such are well constructed and durable pieces but for what I climb they just don't work for me.