James, thanks for the reply. I will certainly submit an enhancement request.
For what it's worth, it was a Red Gate sales associate who actually suggested to me that branching and merging should be performed outside of SSC by a VCS tool. (Must have been over the phone as I can't find the E-mail) I would suggest that if Red Gate doesn't intend me to branch and merge with other VCS tools, that they build that functionality into SSC.
In general though, I would caution against heading towards a proprietary solution that just so happens to use a few piece of another VCS system. I know you're trying to provide a turn-key solution but source control is built around the concept of human-readable text files which can be managed by any client. SSC should be embracing that or it will lose integration ability and nullify features if the underlying source control systems.