By reducing frame, ussually you reduce muscle and bone as well. The cattle will be a bit more calving ease, which in turn will be flatter sided. You can reduce frame and keep all the above, but it is harder than one would think.
We must understand the market we sell into before you go and change your plan. If the commercial feeder calf buyers/feeders don't want smaller framed cattle to feed and that is your market, you better not go to small as they either won't buy from you or they will discount you heavily. Sure you may be able to run more cows on your ground if they are smaller, but how will that help you if you can't find a buyer!
I like a 5.5 to 6 frame cow, and our bull buyers like to buy bulls that are 5.5 to 7 frame bulls. By having cows that are this size, we can hit all the frame sizes needed. It used to be the bigger bulls sold better, but now the commercial cattlemen are extremely smart and go after more than just frame. it seems like they like the 6 frame bulls with gobs of body and muscle. We used to have ring buyers and now they pretty much all have their bulls picked out before the sale and only bid on those certain bulls.
The feedlots we deal with don't want small frame calves to feed, but then again, they don't want real large ones either. The real large one take to long to kill and will weigh 1500 lbs or so, while the small ones get to fat to early and have to small of a carcass, while not gaining as much as they want either plus they have to high of a yield grade.
We buy lots of replacement heifers on order from our bull customers for other buyers around the country and it seems they all want good looking cattle that are deep bodied and are about 5.5 to 6 frame heifers. They will pay a huge premium on this type of heifer if she is good over the smaller ones.
Think of it this way - A few years ago their was a meat processing plant that began and was killing quite a few head a day and was very efficient in doing so, but they went broke because they didn't have anywhere to go with the meat. I believe we need to know our market and sell into it instead of trying to create a new market, as we all don't have the time or money to do so.