I do this every day. I use Photo Mechanic to Ingest my cards, then Rename, Caption, Keyword (using the amazing and fast Structured Keywords panel), then do the initial culling of bad photos, then choose which images will be processed through Lightroom and open them in LR directly from PM.
At work I do not utilize Lightroom's asset management capabilities -- it's strictly a raw processor. A very good raw processor, with some great time-saving features over Camera Raw. At home, I keep my entire archive of personal work in LR, and use it as my primary printing machine, too.
I was unaware you could open them in LR directly from PM! I need to see if PM offers a 15 day trial.