The only handgun scope that I know of with a higher magnification is a Burris 3-12x32mm, which also has a ballistic reticle. Course, it's not a Leupold.

Can't blame you for wanting to stick with Leupold. That's what I've got on my Weatherby, and what my dad has on his. Don't know if I could convince you to get a Nikon or not, especially since you have far more experience with your Leupold than I have with my Nikon, but I can confidently say they are certainly another reliable brand to look into.