Big renovation job - working with a GC or managing myself

Hi!
I just purchased a fixer-upper and will be doing a full renovation (the house was built in 1910 and has had a few additions).  It needs everything: foundation, electrical, plumbing, HVAC, roof, some reframing, and we will move some walls, shift the kitchen around,  and add a bathroom.  

I've been reading all the books on rehabbing and renovating and getting some comparable bids.  have a GC I'm potentially willing to work with.  However, I've thought about managing this myself and working directly with the subs.   I would love advice on whether that is the worst idea ever!  It saves me the cost of the GC fee or we can reduce it if I manage some of it, but there is a lot I need to learn. 

Thanks so much for the help!

kate