Thanks for the info on the LaRue stock!
As far as building an AR15 from the ground up, I'd really rather start with an already completed lower receiver (and upper if possible) to avoid all the tiny parts and assembly (I know, I'm lazy).
Having a Colt is not super-duper important to me, I think they make a great product and Colt is an iconic brand but it's not like it absolutely has to be a Colt.
The 6920 OEM is convenient for me, it is stripped down just enough that I can put together a semi-custom rifle for less without having to go through the aforementioned assembly of the lower and upper receiver. If I am not mistaken, (and if I am, please tell me) Colt is currently the only company offering a rifle like this.