The simple answer to your original question is, buy 1,000 Gamebore White Gold 8's and just shoot them. Consistency in shooting comes from practice and learning the idiosyncrasies not just of the gun but also the cartridge and the combination of the two. I find I shoot better with a 7 1/2 shot size, the difference between 7 1/2 and 8's is minimal but that is what I mentally prefer.
Like others have said, pattern plates offer limited information, you can use them to see the effect of choke but to be honest so will shooting a round of skeet. If you are a recoil wimp (your words...) I would shoot the Evo 24gm in a 7 1/2, I shot FITASC with a very well known professional who used these at that shoot and he won it by a country mile AND the kills were awesome.