I don't know for sure, but a general rule of thumb I go by is if it's a handgun produced since about mid 80s or newer and not a "Ring of Fire" manufacturer, you're probably safe to use +P. The Sigma is a newer gun, my boss owns one. I'll ask him if he's ever tried it in his and report back for ya.
Just read your manual, +P is fine. They recommend not to use +P+, it looks like, though. They give a disclaimer that the +P can cause excessive wear to gun, but that's a "duh" moment because it's higher pressure ammunition.