I would think you'd need to stir it frequently and keep it on a lower heat because of the sugar, but otherwise it sounds good. You might also want to strain the juice just to make sure it's clear.
Pineapple juice is one of those things I usually buy in a can. The juice from Dole is pasteurized and minimally processed. If you're going to cook it down anyway, this might be a less expensive option than using fresh pineapples.