The RC8 begins

[Snipin_Willy]

Been doing some reading and not really sure what the best route to take is. Many buggy users seem to like running 4s. Can someone project a ball park number for a run time using a 1650-1700kv motor on 4s 5000 pack? Conservative gearing no higher than 40mph. I need to be able to make a 20 min main.
Anyone think a 5s 5000 packs are too heavy? In my truggy, I can get 20+ minutes on a 5200 5s pack. I would assume I would get a few more minutes running the same packs in a buggy.
It would be nice if I could use interchangable batteries between these monsters but I don't want my rc8 to be too heavy.