Haven't used one. I have used a BDC scope.. if it works like it says it does it should improve upon the BDC by being able to use the BDC at all zoom levels instead of just at the highest level. Technology is always improving I suppose. The BDC is an O.K. system if used properly. But it's limited in what you can do with it. If you truly want to stretch out and shoot it's not a good option. But it does have it's place.
-Jake