Honestly, David, I don't think anything the existing DS fans could have said or done would have made the difference we hoped for.
TV networks deal in staggering amounts of money....and we can never underestimate what that means for the things we actually get to see on TV.
I don't think it would have made the difference if they had heard from every single person who ever went to a fest, or posted on a DS related site......we simply don't number in the millions, and those are the numbers they want watching their programs. Add to that the fact that the network has indicated that they have a whole working theory that revolves around "family oriented" stories, and it's easy to see how DS would not have fit into their over-all plan
If the show had gone on the air, and attracted a sizable new audience, then, I think, mounting a campaign might be the sort of thing that could save a show from being cancelled.....but I really don't think our support (or lack thereof) for a new, untried product, would have swayed them either way.
How fans treat one another at fests is another matter altogether, about which I can't comment because I've never attended one. But I will say that I've been on this forum for more than 2 years and have found the folks here friendly and respectful much more often than not, and truly bad behaviour is never tolerated.
Whatever anyone else did or didn't do.....if you did what you thought best, then you have nothing to regret.