I really can't answer that, Stuart. It is more a personal thing if you prefer the 706 or 857. Note
that the RemoteRig support for the 857 is fairly recent, so there is probably more experience
available in the community for the 706. But this may be a moot point within a year or so, since
I believe the 857 sells better.
Perhaps someone can chime in that has used both rigs, I haven't used either one myself.
73,
Mitch DJ0QN / K7DX