Shortgrass,
Since the Char cross commercial female is a rather common occurrence in Canada, crossing back to either a Red Angus Or Hereford bull is a routine thing done to keep the hybrid vigor up and to make sure the calves don't get too white. As long as you choose to use say a good Hereford bull on your RA X Char cows or a RA bull with HH X Char cows it works first rate.
If you have the feed the Sim-Angus and other Angus/dual purpose continental cross bulls are becoming more popular as you keep more of the growth and milk found in continental breeds and the pay weight hit at weaning for using a lower growth breed is reduced.
The bulls to be used on these Char cross cows tend to be a higher performance version of the British breeds since the Char cross cow can handle more birth weight.