Vince,
Here is my take on the AI deal. First of all only use AI on the heifers and about a 1/3 of the cows, so most of the cows are bred to a single bull, the heifers are cleaned up to a different bull, plus some of the AI cow group.
I dont know about yours but my cows are all alittle different, for example some might need frame, some milk, some muscle shape, some need multiple things. I use AI to tailor to the little things those cows need. The AI bulls and the natural service bulls all have traits in common like size,shape,feet and attitude with small differences. I believe they will produce a ~ 6 Frame Steer that will go on feed to weigh 1350 lb at 14-16 months in my management program. They will also produce a female that will have the look, milk, and fertility to work for me or my customers.
I do also have a small linebreeding experiment to a bull that I think puts all of those things into one package, in 15 years I will let you know if I am right.. If I am wrong I will be happy to eat the mistakes.. LOL.