I don't know... I think Amanda has carved out her own niche fairly well with this show. She's so far removed from Samantha Carter that I don't think it would be a problem. Not to mention, they
are all actors after all- the stretch of playing an entirely different character across from someone who also used to play a totally different character
with them before would probably be a welcome (and fun!) challenge. And I never once confused Ben Browder and Claudia Black for their old Farscape identities while they were on Stargate. It never once crossed my mind that these two were ever supposedly in love in a whole other universe.
That's the strength of a) good writing and b) good actors.
Also, I think it's just a good karma thing- I haven't seen Shanks, Browder, Judge- or most of them come to think of it- in much else since the shows ended, besides the movies. (I can't picture RDA on Sanctuary at all, for some reason?
) I think a paying gig would be greatly appreciated by most, especially since they all clearly liked working with Amanda. Oh- I'd love to see David Hewlitt. That would be awesome.
Lastly, who's to say that most people watching Sanctuary are even SG1 fans? They're not exactly the same sort of shows, really.
I don't know. Just my 2 cents (or more like 5!). I personally would love to see any of them on there, and I think that since most of the episodes are one-offs (i.e. not necessarily attributed to a greater story arc), it would be entirely possible without feeling like a sort of cheat.