I just want to chime in here and say that I am PLEASED with this debate/discussion.
If i started this on any other forum well by now it would have descended into Chaos and I would have been forced to call in the Jem'Hadar[Moderators] Trek BBS is already making me feel so much better now that I've found a good place with other Trekkies here!
I think the key thing is that when you Join the Dominion is that you set your terms [reasonable of course] with the Negotiating Vorta. After all if they simply aren't interested in you [like as a I said a small colony world far from anyone else and not really a strategic position for anyone] You CAN benefit from being protected by the Dominion.
After all a Small Colony world that just minds it's own business and doesn't get in the affairs of others shouldn't be a problem at all. Sure there might be a few groups that wouldn't agree with the governing body's agreement but then again being part of the Dominion is preferable to being Invaded and having so many of your citizens killed when all it would have taken at first is skilled negotiations.
Small Colony worlds probably don't have their own military but at least have some security forces. Over time, you would come to accept the Vorta and Jem' Hadar as friends not enemies and simply agree to their requests that they make and if you have a problem with them you can simply talk it out.
I myself wouldn't mind having a Vorta for a Friend,they could offer so much advice from the Dominion's standpoint on so many things [that I know of]
In fact if you were to get your own defense force trained by Jem'Hadar even they would get put back in reserve and would benefit from that combat Training and might prove their value to the Founders.
After all who can't forget what they say?
Obedience brings Victory,and Victory is Life.
http://memory-beta.wikia.com/wiki/Dominion