I just bought the 4200 last year, for my grandsons, but sitting in stands with them I will occasionally get a chance to look through it. It is very bright (some of the optics professionals on the SWFA site rate it very close to the quality of the Conquest). There probably isn't any appreciable brightness in the 50 mm over the 40 mm. Plus you get the RainGuard feature. As far as the 50 being too much, I use a 56mm Diavari and have had another 56 mm scope and I can't see the problem that other people have talked about. It isn't but 16 mm larger than a 40 mm which when split would be 8 mm which is just over 1/4 inch in additionaleye height.