I say, don't listen to others because I believe you can make a better choice for yourself if you research and find the information you need to get what you want. People are to bias to listen to in these matters. Proven facts and your own feeling are better to go off of, not some one else's option.
What do you call research? It looks like this could be a piece of the puzzle to help him make a decision!
Just because you can kill a fly with a hammer - even an expert is not perfect and a 410 will not kill as many ducks as a larger gauge. That is like saying a 22 is a great deer rifle. It will kill a deer but it is not a wise choice.
Different guns have different points of aim. My o/u sporting clays gun shoots a little high- so does my SBE. My m90 shoots a little low my nova and bps shoot dead on. I can tell a difference for a few days when I change up guns. I can still hit with them but not as regularly as if I stick with one. When you practice with a gun...you get better with that gun if you do not believe that logic I might as well quit here.
There is an old saying, "Beware of the man with one gun who knows how to use it". If you practice with the same gun you hunt with you will be use to the balence, feel, and what you can do with the gun. You will be more effective.
The man asked if there was much difference between the 12 and 10. If you think 8 #2 pellets is alot I'm not going to try to change your mind. If you would rather have a 10 1/2 pound gun instead of a 8 lb....by all means go with the 10. If you are deciding between the ballistics (and to save confusion we'll say factory load) there is not much difference. If you want to shoot very heavy loads at teal and wood ducks (early season) or on short range shots go with the 10 -your going to have trouble finding a light load. If you think most of the time a 3" load is ok and when you need the extra range you would like to throw in a 3 1/2" and be able to use a lighter, quicker gun, and an easier to find shell... the FACTS say go with the 12.