I haven't found a damn DAM that really seems to work for me, universally. I've used a few different programs. Like you, I've been using Lightroom, but for certain projects only. I also own, and sometimes use Extensis Portfolio and also ACDSee Pro 2. Sadly, there is no universal way of tagging files or rating files so other programs can use it. In a way, for editing, I've yet to find a program as quick and easy as BreezeBrowser. I can see it all getting, way, way , WAY ahead of me and out of hand, partially because of my own reluctance to standardize on one particular program. Like you, I've seen the limitations of each and have a hard time reconciling what I'm willing to give up.
Another program to throw out there, that I've always heard good things about is Thumbs Plus. Part of my reluctance is the "orphan software" syndrome. Too worried about a company going under, being bought, or otherwise abandoning the software I finally decide to adopt.
I've tried cataloging 3000+ images from a book project with Extensis Portfolio. A failure. I finally used LR, which actually made the task fairly straight forward. At this point, no images are CMYK, which is LR's Achilles' Heel when it comes to acting as a DAM. ACDSee has done a pretty good job with the project as well, plus you don't have to import them into the program (what I hate most about LR).