I took different ones (Citrucel the longest) for almost a year, and then was suffering from such severe bloating that I quit them cold turkey! I have been better ever since.
It's nice to not feel like I'm 9 months pregnant. My stomach is actually flat somedays. I had forgotten what that was like.
For me, it's better to just eat sensibly. My body just doesn't tolerate the SF. But everyone is different.