In my opinion, the Forensics/Security degree would give you the ability to see both sides of an attack as well as the ability to work in a pre and post attack phase. One of my undergrad degrees is in information assurance, where I had classes on protocol vulnerabilities and ethical hacking. Obviously, I was able to learn methods of gaining access to a system and how to cover your tracks once you're in. Now, I'm working on a MS in forensics where I'm currently finishing a class on network based forensics. From here, we've looked at log files and other evidence that could be used to determine if/how an attack occured.
By already knowing what an attacker looks for when attempting to gain access to a system, an investigator will have that little insight into other places to look that an investigator unfamiliar with hacking techniques may not be familiar with.
Of course, specializing in both also provides the added benefit of being more well rounded and having a slightly better chance of locating a position upon graduation.
Hopefully this helps!