Hey dude, I collect NFL jerseys and I can relate to how you feel about wanting as close to the real thing as possible and navigating through murky NFL jersey waters. Here are my 2 cents regarding elite vs on-field & and pre-made vs customized:
I collect my jerseys to wear. Most NFL game worn jerseys appear difficult to pull off wearing, due to their long elastic bottom or the sleeves being very short, or simply because the jersey was designed for a 320 pound lineman.
However I own one Nike elite and it doesn't even fit that comfortably. As far as the differences between elites vs game worn...the elites appear to have smaller nameplates which irks me. Also, some teams also did not adopt 100% of the Nike jersey changes initially, so it can get very confusing and difficult to try to get a wearable jersey that's exactly what the players wear. I personally am happy with a collection of "retail authentic" jerseys, but I wish Nike would make adjustments to make their jerseys closer aligned with the game worn jerseys (bigger nameplates, elastic sleeves, etc)
Unfortunately I have heard bad stories about ordering customized jerseys when comparing them to the pre-mades. If you have time to go through this thread: http://niketalk.com/t/332565/2015-nike-nfl-apparel-footwear-jerseys/2880, you can get some insight on the pre-made vs customized struggle. I am unsure whether if you order from fanatics, nflshop, or the team store, if they all get their jerseys from the same source. I would love to know the truth. I would probably avoid fanatics if you can help it.
Based on what I have seen/heard, I am unwilling to shell out the dough for a customized jersey because I am sure I will be disappointed with the results, which is a shame because my favorite jerseys are the obscure ones where customizing is necessary. And depending on the team, you don't really have many player options for pre-mades in 2015.
I hear rumors here and there that Nike Elites have gone through changes and maybe they are more comfortable now. I have a bumblebee Polamalu, which I placed as a customized order in 2014 (before I knew better). Fortunately, I the jersey I received was old pre-made stock (circa 2013 probably).
If you do find any new information, please let me know as I find this all interesting. Hope I didn't come off too cynical; I am very enthusiastic about jersey collecting so all these issues between elite vs gameworn and premade vs customized bother me more than most, lol.