I think the moral of the story here is that there are many options when interfacing a security system with crestron. I have been installing both for about 5 years now and have used HAI and Apex. Both are very robust and have an adaquet protocal for communication. And the moduals for communication with Crestron are all ready written (big time saving factor there). But it all boils down to which one will fit your needs and how good it the programmer that is interfacing the 2.
There really is no right or wrong answer here. Just wich one do you feel most comfortable with. So I dont think your going to find an easy answer here.