When I was 'researching this topic', I did not find what felt like was a solid source of information. Certainly nothing like a Consumer Reports analysis of vacuum cleaners, for example.
I came to the conclusion that the attitude and competence of the installer/service place is a very important factor here. Along those lines I would avoid any place that isn't dedicated to servicing IID's (as opposed to Joe's Auto Stereo Shop). And I would 'just drop by' for a chat to make as good an assessment as possible about their competence (tough to evaluate) and attitude (much easier to evaluate).
The internet is chock full of anecdotal stories (typically horror tales - not much out there saying "let me tell you just how good my XYZ IID device is"). Like much of the anonymous stuff out there, take it as the truth at your peril. And the sources of information (those with DUI's for the most part - like me) do not represent the best possible pool of folks from which to be getting anonymous information. But there probably is "some signal there inside all the noise", regardless.