Got links?
I didn't think ACM made guns, I can't think of anything else they've done in the past. Not a big name that's for sure, so their QC might be questionable. However I have a number of ACOG scopes and stuff that are made by ACM and they're all really good, so I guess you could argue it either way.
I'd probably buy something else though, but I'm not sure there are all that many options if you're after a Famas, I can't think of any company other than Tokyo Marui that make them... Others might though.
As for Cybergun, they're actually just a licensing company, they have the legal rights from the real gun manufacturers to stamp the real gun's trade marks and logos etc etc onto the airsoft versions, so they just buy an existing company's guns and then stamp stuff on them.
So depending on what the company is that makes that Sig, it'll either be good or bad.
Anyone else have any input?
Links would certainly help.
I'd say the most important thing is knowing what a company's reputation is like, then searching for a gun based on that. As opposed to just searching for guns without any knowledge of the company that put it together.
I'd say the best companies out there at the moment are G&G, ICS, G&P, VFC and Classic Army - See if you can find a gun you like made by one of those companies and you can be relatively sure it'll be good and reliable.
If you're on a budget then I think all of the above companies with the exception of G&P and VFC make all their guns in both plastic and full metal, so you can always go for the plastic offering if you want to keep the cost down.