westy,
The BR models have a few advantages over the NXS for benchrest. The optical path of the BR models is slightly longer and theoretically offer slightly better resolution. Both are very good and any actual difference doesn't amount to much. But the important difference is that the BR models have 1/8 minute click adjustments and the NXS has 1/4 minute clicks. This is an important issue in score games. I think the BR models are slightly lighter which might make some difference to you if you're close to making weight. Finally, the BR models enjoy a significantly lower price than the NXS models.
Greg