Best of luck in your endeavors.
some hybrid vigor 101:
Bristish Breeds (English Breeds) are Angus, Hereford and Shorthorn
Continental (European, "Exotic" (back in the day)) breeds are those developed in Europe such as Charolais, Limouisin, Simmental to name the biggies. others like gelbvieh, blonde d'Aquitane, etc
All the above are of genus Bos and species taurus
Bos indicus (different species here) Breeds are Brahman, Gyr, etc (wont even pretend to know all those names)
Maximum Hybrid vigor is supposed to be obtained from mating genetically different species so you would get the most out of a mating of Bos taurus with Bos indicus. the offspring of a mating of for instance brahman and hereford would have 100% hybrid vigor. The next best is a three way cross bewtween Bos indicus, a continental, and a british. i think like 77% hybrid vigor is achieved here.
So it stands to reason that continental x british should be better than britishxbritish b/c they are less similar.
But anyway, if it works it works. who cares. i like all cattle.