I am exactly in the same boat.
Tonight a guy interested in buying my IN72 came to see it with his wife, and he will tell me their decision tomorrow.
I intend to replace my IN72 with an HC1500... I know the IN72 is the best-looking projector ever, and I am kind of sad to sell it, but remember: Blu-ray has just won the HD battle, and people are becoming more and more aware of Blu-ray's existence, so it will become more and more difficult to sell an old 480p projector. The small window of opportunity to upgrade to 720p is now.