I've got the 1 mile arc. My dad has the 1000yd vortex (I think its the 1000 anyway).
I paid 230$ for the arc, I feel it's a good buy for that price. It will range rocks out to around 1400 relatively easy if your holding good and stable. I think its be better off a tripod or a more solid rest. Furthest I've ranged animals in the field was 730ish, on antelope in Wyoming. Ranged cows just over 1000 with it. Need to do more testing to find it's limits.
Build quality is good, same warranty as vortex, but with worse customer service.
Dad's vortex is awesome. Have only played with it a small amount, it's physically much smaller then the arc, I prefer the arc as I have big hands, and it's size makes it easy to hold steady with both hands. The vortex is much nicer to carry, fits in pockets easier.
I'm happy overall with the Bushnell, but I do worry that when something goes wrong with it, I'm gonna be wishing it was a vortex.