I've used a couple of different types of range-finding scopes in my lifetime, which is why you'll never see a "BDC" scope in my shopping cart at Gander Mountain.
Big game, center-fire, hunting rifles are best equipped with scopes of low-to-modest power, with a single, uncluttered reticle that is either a fine wire, or some kind of duplex reticle. Added lines, or what I refer to as "silly circles" just confuse the issue and give the shooter a false impression concerning the relative capabilities of the cartridge or scope on their rifle. Such a scope can even mislead the shooter into thinking he's justified in attempting 400 yard shots, when he hasn't practiced at that distance very much, if at all. I know, because I made those mistakes when I was shooting with scopes of this type.
The better solution is to chronograph your bullet (if you don't, the BDC is useless, anyway), use any decent ballistics software to print a drop chart and sight in for maximum point-blank range. For most cartridges, you're going to be between 250 and 350 yards, and that is PLENTY, for 95% of the shooters out there. Then, most important of all: Practice at 200, 300, even 400 yards, so you actually know what your gun is capable of at those distances, and whether or not YOU should even consider shots that long.
Back when I had scopes that were supposed to help me shoot at 400 yards, I was NOT capable of doing my part. Later, after I had practiced quite a bit at 300 yards, I actually came to realize that 300 was quite far enough, thank you. I also learned that you don't need 16 power, or even 12 power magnification to shoot to the max PBR of most guns, and you certainly don't need any confusing lines or circles to "help" you do it.
I know I'll get flamed, and that's fine. This is really just my opinion, although it is one I share with a lot of experienced shooters/hunters. YMMV, n' all that.
