You need to find the right SFS and the right dose for you. Then most people find the SFS REALLY helpful. I wouldn't do without mine now!
Unfortunately, a lot of the better known ones (therefore the ones usually suggested by doctors!) have sweeteners in and are generally psyllium or inulin based, BOTH of which are hard to take and have more side effects. The one my doc first put me on (before I discovered Heather and Acacia) was psyllium based with sweeteners and all kinds of additives. It made me so bloated and gassy, but it STILL helped my D and pain.
Acacia seems to be one of the gentlest out there, unless of course you seem to be allergic to it like poor Dalia!