1. As a Canon shooter myself I don't see any benefit whatsoever to using DPP.... especially with the new DNG Profiles from Adobe. You can precisely reproduce DPPs raw rendering in LR, and so far, the only thing I've seen in DPP that I can't do in LR is see what autofocus points were locked at the time of capture. I think this is insignificant.
2. In June 2007 DxO released the first Lightroom plug-in, designed to integrate LR with Optics Pro.
More info hereI haven't used this method, and honestly can't vouch for it, but just wanted to let you know that DxO is totally onboard with LR plug-ins. I think you can expect to see much more interoperability in this regard during the coming months.
IMHO, the benefits to DNG and Lightroom far outweigh any disadvantages. Having your XMP embedded in a single raw file represents a HUGE advantage in high-end imaging. I don't see any need to keep .CR2 files around.
Before you rule out DNG, I think it would be a good idea to take some time to really map out your desired workflow more thoroughly and consider whether you really need to keep those .CR2s at all.