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.
Just because something has a duck bill doesn't mean it's a platypus. It might just be a duck.
Roger Miller: You can't roller skate in a buffalo heard, but you can be happy if you've a mind to.
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.