Sorry bigag, but I disagree with your assumption that because a bull isn't multi-generations of a purebred or fullblood line that it should be a steer.
As a kid, we were taught that crossbred bulls were a no no. That there would be too much variation in the offspring. Apparently the chicken and swine folks didn't follow that philosophy and they have produced a very consistent product, and now 98%+ of commercial swine is produced from hybrid (crossbred) genetics, and 99.9%+ of poultry is also produced by hybrids. Over they years I have looked at thousands of "crossbred" cattle (i.e. Brangus, Chiangus, SimAngus, Gerts, Balancers, Lim-Flex, etc.) and I'm not convinced that there is a noticeable difference in variability, compared to purebreds. Actually I probably see more variability in many registered Angus herds because of the wide genetic base in the breed. So if an Angus breeder is either trying to change course in midstream (i.e. breeding for smaller, "more efficient" cattle) or trying to produce bulls to meet different market segments (calving ease, high quality grade, and high growth terminal cattle) there is a great deal of variability in the pasture; and they're all purebreds.
I agree that to maximize heterosis, a producer should run crossbred cows of complimentary breeds, and breed them to a third breed. However, I know of large operations (2000 cows or more) who have given up on maximizing heterosis because of the headaches of trying to accomplish this. For example, if you produce your own F1 replacements, you still need to maintain a separate herd to produce the F1's. If you decide to buy your replacements, you need to find a ranch that can produce the replacements in the quantity that you need and run their cows in environments similar to the way you run yours. This doesn't sound all that hard, but if you need 350 replacements a year, and you want them from a single source, it can be a real struggle trying to find a ranch that can do that.
Many, many, many large commercial ranches have realized that they can maintain some heterosis by using hybrid bulls. I believe I read in BEEF magazine a couple years ago where Bell Ranch is breeding SimAngus sired females to Balancer bulls and vice versa. They still maintain a 50% Angus 50% Continental herd and get some additional heterosis by using both Simmental and Gelbvieh influenced genetics.