AJ, I'm working on my first flip as well and I'm wresting with the same question. I have project management experience from the IT world and some stellar subs in the rolodex but I'm going GC on this first one for 2 reasons.
1. It's my first one. I don't know what I don't know. So for this first one, I am paying the GC to know everything I don't. I'm going to be confident I have the right GC when I find one that is willing to answer a LOT of questions. I'm looking at the extra money spent on the GC as an educational expense.
2. I like things that scale. I have a TON of life responsibilities outside my real estate adventures and so if I were to manage all the subs myself, it would severely limit my speed and volume. I couldn't do more than 1 at a time and the other areas (leads, networking, learning, etc. would all fall by the way side). For the GC, this is their job and so they can specialize in what they do best while I pick the things they cannot do.
Long term, I may go the way of a Project Manager that can handle those types of items for me; again, whatever I choose has to scale. Hope that helps.