AdSense has not performed and the more I read about CPMs and lousy fill rates, the less hope I have for them.

Unfortunately, every affiliate program I have found for my niche has a forum of its own dedicated to the same niche at its website!

I don't want to risk losing members to competing forums, but I have to figure out some way to make money from the forums to pay for their costs...

Should I join these affiliate programs, promote them, and hope my members don't jump ship to their forums either while browsing their store or when reading one of the many promotional emails the store would likely send them after a purchase?