I had trouble on my 100lb FC live bait rigs in 10-12 years ago using Ali crimps, the crimp would compress the FC together and crush it [splinter], once I changed to Fig8 Copper sleeves I never had a problem. The Ali is OK for mono but the copper still do a better job IMO .
I used to think the same... but then I did some tests of my own.
I have a simple test I do with every single game leader/rigging before it makes it into my tackle box with a 25kg set of scales. If it can be pulled to 25kg it passes the QC test
Anyway, one day I'd just finished putting 120lb Jinkai on a heap of Tuna Feather lures using fig 8 copper sleeves... and they
all broke @20kg(give or take a few kg). I then recrimped with ali and they
all passed the 25kg test!
Dont get me wrong, I do like using fig 8 copper crimps, but I think they do have their limitations... on lighter Mono, if I can fit 2 X fig 8 copper crimps on they get a show or on 250lb plus mono there's no dramas.
I dont know about FC... I've never tried comparing the 2 crimps, but when I use lighter Mono... it's "ali" all the way.
Dont take my word for it... do your own tests.