I believe this hobby is about trial and error. Since there is not much data out there concerning this type of set-up, why not try it. Sure take heed to all of the warnings and then try to work around them.
In nature, clams and other creature are excellent filter feeders and they are known to keep the water quality clear. Such is their lot. So yes, one should be careful when or if they are going to add them to their tank, but on the reverse, someone could possibly come with a solution that would become the standard in the hobby.
All critters are dangerous in the aquarium when they die and are left there.
All I'm saying to you Aribenlaw, consider the warnings, but don't let them deter you from trying something new. Keep track of your successes and unsuccesses. I believe it was Thomas Edison that said, "I didn't fail X amount of times, I only learned X amount of ways I COULDN'T make a light bulb." So try the bivalves if you choose. And if you need to, post X amounts of ways to keep them succesfully or X amount of ways NOT to keep them.