Well first off, for anything that you had to use Photoshop for instead of Lightroom, Capture One won't do the job either. So, if you need PS when using LR, you'll still need it when using C1.
I tried C1 a while ago when I found out about the Sony version. Their image processing engine just seems superior to Adobe's.Colours, sharpness, noise - all just look better. Skin tones especially are easier to get right. Just using it, I get the feeling it's capable of a lot more than LR.
The problem is, it's just so different from Lightroom which I now have years of experience and familiarity with. The interface is far more flexible, but in return feels far more cluttered and disorganised. I'm sure there's a bunch of handy keyboard shortcuts that would help, but even if I knew them, they're not muscle memory like the Lightroom ones. The layer system seems powerful, but having to have an entire layer per clone/heal is incredibly clumsy and bloated. The flexibility of colour channel manipulation seems far more powerful than in LR, but the degree of adjustment possible seems far far lower. Have a local adjustment selected in LR and hit delete - it deletes the adjustment. Have a local adjustment selected in C1 and hit delete - it deletes your photo. Split toning only works in B&W. Dozens of other quirks and annoyances.
As you said - it would be an enormous time investment to learn it properly, and maybe then most of the annoyances would go away - or maybe they wouldn't. Maybe I'll give dxo optics a try sometime.