Comment Data about the Crashes and Safety Implications (Score 3, Informative) 367
In general the data seems to suggest that yes, total crashes at the intersection will decrease (CMF = 0.8). CMF stands for Crash Modification Factor. Right-angle crashes will decrease (CMF = 0.67) and are generally more severe than rear-end crashes. Rear-end crashes may increase though (CMF = 1.45). Both groups generally tend to loudly argue their own point and both may be correct without listening to the whole safety argument.
See http://www.cmfclearinghouse.org/about.cfm and then search for "red light" and you'll see what I mean.
All of this doesn't sort out the monetary costs and privacy aspects of the programs, but the safety data is reasonably easy to figure out so they can stop arguing over it.