hi holgs - as was probably fairly obvious, I researched the heck out of exclusivity versus non-exclusivity. my decision was to remain an exclusive on iStock. there are many reasons, but the greatest reason is that I can't really imagine not being exclusive. I think iStock has an incredible collection of images, and despite my sales angst (which is still fairly acute), I believe things will improve after getting tons of invaluable advice, and after some very intense and helpful conversations with iStock admins.
I also believe that many iStockers go through a similar rite of passage. questioning exclusivity is like transitioning from teenagehood to adulthood.
I'm about to hit gold, looking forward to increased royalties and the new canister.