I have stayed out of this one, but not now. Calling your advice irrelevant is not belittling. You are both grown men.
1) He mentioned fit as being paramount. It is. He did not mention paying. You do not need to have any work done to get a shotgun that fits beyond doing a google search and watching a few videos, after which you walk into the gun store and shoulder the guns they have. Easy. Now that didn't cost anything. In fact, here are a load of videos that teach about proper fit that at one time would only have been possible by going to a trap/skeet club or a gunsmith specializing in shotguns.
https://www.google.com/search?q=how+...w=1093&bih=532
2) I have tried to understand your talk about ultra magnums, but correct me if I am wrong, "ultra-magnum" refers to a family of centerfire cartridges put out by Remington, of which many of us have had some. Where does "ultra magnum" enter the world of shotguns?
3) Your advice of a single shot or bolt action for practice to sharpen form may be okay, but only if that shotgun fits. There we go with that word again, but it is the most important word in the shotgunning vocabulary. Problem is the OP is asking advice on a semi-auto he wants to use for hunting. Further, why would anyone go to the considerable cost and trouble of outfitting themselves for goose hunting, and then handicap their ability to harvest birds with a bolt action or single shot? I learned with a single shot when I was 12 and then Dad bought me a Marlin Goose Gun bolt action with a 36" barrel. Bad mistake. Why? It didn't fit me as a 14 year old worth a tinker's damn. Worst thing you can do to discourage a new hunter is give them a gun that doesn't fit because it is much harder to hit birds.
Keg, relax man. This is the internet. Put Elk on ignore if he bothers you, but the advice he is giving is correct.