Guess my experience has been different. My brother has broken 3 belts in the last 4mos and is now on his 4th belt.
Does he ride the crap out of his bike... yep, sure does but, if he'd had a chain he wouldn't have been out that 600.00 on final drive belts plus downtime etc.
I guess it really depends on how you ride. I'm not saying that everyone needs a chain conversion but, once you go much over 100hp you have the potential to break em without dumping the clutch.
I've heard the general rule stated that when you build a bike, you put a belt on something with less than 100hp and a chain on something with more than that so, if that is a true rule then, as soon as we start putting hot mods on our bikes, we have the potential to break belts. ( I'm not saying that I've broken one yet on my bike but, you never know )
I don't see the immediate need to do it but, I may want to at some point. ( Like if I break even one belt )