Here is my .02. I just got the Nikon BDC for my Swift and so far haven't had to use the circles out past 300 yards. What I can say is, the shots I have taken with it, have been crisp sights, fast on target, and consistently accurate. I can't wait until a Prairie dog or coyote gives me the opportunity to fling a bullet at it out past the first circle to give it a try.
I watched a friend sight his in (same scope on a .22-250) and he was consistently hitting the plates at 300,400, 500 yards. That is what impressed me to get one on the Swift.
As for a Leupold, I have a VX-3 3X9-40 on my .270. I had some serious issues with keeping it zeroed. I don't know if it was all the scope or if the rifle, or ammo, was the blame. I bought a Rem. CDL SF for a large game rifle, and for it's supposed accuracy out of the box, and after the first cow hunt I went on, I felt cheated. I just about left that POS in a snow drift on the mountain. After the hunt, I tore the gun down and reset the guts in the stock, floated the barrel, and a few other accurizing tricks I could think of, and finally got it to shoot half decent. Last year I drew a good deer tag and wanted to try the .270 (and it's ability to shoot flat at range), so I asked some friends in Wyoming for a hand load recipe, figuring they know how to shoot long range in the wind. Worked up the loads and shot the crap out of it, until I had some confidence in it again. Took a nice buck at 300 yards, hit it 3" high, which is where I was aiming, thinking I would have some bullet drop. NOPE. The crosshairs on the Leupold was nice on the big bodied buck, where I think the circles might be too big, to be hair splitting accurate. Don't know that for sure, but the coyote I shot at 300, the circle was most of it's body.
So, after all that, it's going to come down to one thing. Do you want to play the guess the amount of holdover game (which hunters have done successfully for years) or get the BDC and have the yardages mapped out for you already? Point and shoot.
A friend of mine runs a sporting goods department here and sells Vortex. He has one of the rangefinding scopes on his .223 and I've shot it, I was impressed. Especially when you get the MOA adjustments figured out like he has. Shooting prairie dogs at 700 yards is a good time.
Check them out if you haven't already. Good glass, decent pricing, and the best warranty in the business. Just my opinion.
Hope that helps and wasn't TMI.