So I know that proxying is allowed in ITS as long as you use a Corvus Belli model, but does this also apply to models that have been removed from the game? I was thinking of using Haramaki to represent the Wu Ming for my Ikari Company and I wasn't sure if that would be something I only get to do in casual games.
Talk to the TO. Always talk to the TO (who'll usually also be a warcor). Has been years and years since I last saw someone complaining about TOs being restrictive when it comes to proxies on the forums, so you'll probably be safe doing that proxy. Just keep in mind that Haramaki look more like ninjas than heavy infantry :p
Yeah, the golden rule is that remembering which model represents which unit should not be confusing to either your opponent or to you. Having an HI stand in for HI, using a model that’s not normally in the faction, with weaponry that broadly fits the appropriate class (rifle, rapid fire, large ordnance, etc) is completely appropriate.
Yeah, basically Silhouette (and therefore base size) needs to be the same. The model "looking the part", having the same or similar weapon type, etc. is a courtesy because Fifteen Unpainted Warcors instead of the appropriate S2 Troopers would be legal, but a bit of a dick move :D
These aren't just legal, they are often the BEST proxies! Why? Because there will never be any confusion about something being the wrong unit. Even if your opponent knows what you are using to proxy, it'll always be obvious that it IS a proxy.