As I pointed out earlier, larger objectives don't necessarily have to had any significant amount of extra weight - yet everybody is parroting off that this is as part of the reason why they don't like larger objectives. The extra aluminium and glass will add about an extra ounce, at most two. What tends to make larger objective scopes heavier is all the other "features" they come with - including superior lenses, but also a lot of things I sincerely doubt the real world utility of.
To put things in perspective, my "default" scope is the Swarovski Z3/AV 4-12x50. It weighs about 1.5 ounces more than their 3-9x42, and just 2/3 ounce more than the Leupold FX-III 6x42! It is more than half an ounce lighter than a Zeiss Conquest 3-9x40, and most other 3-9x40s on the market. Big objectives don't have to add much weight, yet they most definitely add time to my hunting day. And I have my 50mm objective mounted just as close to the bore as you can get your 40mm, due to the mounting arrangement. When you are hunting without curfews, like most of the world does, that is an extra 30-60 minutes hunting a day at little or no extra cost in weight, ergonomics or bulk.
If you hunt exclusively in North America, there is probably little reason to go reason to go to a 50mm objective. But there are good reasons why the rest of the world hunts with larger objectives. This also explains some of the "different" mounting systems that you see on rifles made outside of North America - the best example being the mounting system on the Blaser rifles which pushes the mount forward onto the barrel, allowing for a larger objective to be mounted lower to the bore.
