I just acquired a bottle of Cuiron and have been a big fan of Bel Ami. I've only sprayed Cuiron on my wrist but I do notice some similarities. Mostly it's in the leather and an almost citrus topnote. I think Bel Ami is more complex and adds a different demension with the addition of some spices. I don't see too many similarities in the drydown, Cuiron is more powdery and sweet than Bel Ami which is much more herbal to my nose in the drydown.
I have not smelled Acier Aluminium but I would like to.
I've frequently worn this scent when in "close proximity" (dates, clubbing, etc...) with women and have had nothing but overwhelmingly positive responses to it. I have the newer version as well, from all reports the original formulation was much better, if that's the case it must be amazing.
I haven't worn it since it's gotten warm, but I wear this one a lot in the cool weather. I'm glad I got a large sized bottle and this is probably one of the few frags I would buy reserves for.
EDIT: I did wear this last summer in Vegas, 95 degrees+ at night, and it worked rather well. I think I also wore it a couple times here in the Pacific Northwest summers last year. It's probably best as a cold weather scent, but I think it can work just as well in warmer weather.