Driven by despair with LR's terrible performance I have been searching for an alternative and came across ON1 also. It's good but it's not the same. It's really a viewer with bells on, and the virtualisation is closer to the original iPhoto system - edits are made on a copy (you can choose Jpeg, tiff or psd) - so you get your original and the edited version both on the HD - the upside is either can then be processed by multiple apps and not just the built-in one, the downside is more disk space - especially if you're using psd or tiff.
From a DAM point of view it's good for managing files - which can be in multiple locations - and it has Albums, keywording and so on. On the downside, the Smart Albums are not so sophisticated - I can't find a way to find images 'not labelled red' for instance, no Places feature as such so it's by no means a perfect copy.
That said, I'm quite liking it so far, but really only exploring it on a few thousand images. It's worth declaring my interest - I'm a hobbyist shooting Raw, but I have other family members who are shooting with phones or P&S. I need an app that can somehow work for both. I've explored Capture One (very good) but that's too much for the others in the house, but Media Pro looks good as a Catalogue.
I think Media Pro is due a serious upgrade, and I might look again when that comes out. On1 have a new app due 'this fall' a Raw processor with true non-destructive features, and I'll have a look at that too. Right now, it's the 'most likely' contender... There is a 30 day free trail, check it out.