jathames,
Some people will say no, but I say yes. To me, the 50mm objectives, even with a 1" tube, seem brighter than the 40mm versions when dealing at higher magnifications at low light conditions.
For example, a 50mm scope set on 10x will give you an exit pupil of 5mm. A 40mm set on 10x will give you 4.0mm. Is 5mm better than 4mm? Yes, is it worth the extra money? I think yes, but your pocket book can better answer that question.
Also, what most people seem to overlook is that, even though the exit pupils may be big at lower magnifications, it is still very nice to have. Why? Because the greater the eye pupil, the more area your eye has to move around and thus not have a problem with eye alignment. Think about it like this - your eyes have more room to move around when looking though a 2" pipe than a straw.
Some people may also tell you, and to some degree rightfully so, that all of the above is really not all that important in "real world hunting." Okay, maybe so. But when I go hunting, I want everything in my favor.
Let me give you a caveat. You should also understand that what I am telling you is based on optics that are the same quality i.e. comparing an Elite 4200 2.5x-10x-50mm vs. Elite 4200 with only a 40mm objective. DO NOT THINK THAT CHEAPER QUALITY OPTICS WITH 50MM OBJECTIVES ARE BETTER THAN HIGHER QUALITY OPTICS WITH 40MM OBJECTIVES. In orther words, don't think that, say, a Tasco with 50mm objectives is better than a Swarovski with 40mm objectives.
Zachary