If you've never had problems with your HD70 you must be the luckiest person on this planet! They are TERRIBLE for overheating. Mine started doing it at just 1200 hours! I had to take the whole thing apart and clean out the fan that cools the color wheel. I had to keep doing it more and more frequently until finally that wasn't enough to keep it cool anymore. Since then I've had to gradually get more aggressive with my cooling techniques using an 8" clip on fan. Every time I find a new way to make it stay just cool enough to function about 2 weeks goes by and it starts messing up even with that fix. Right now, and this isn't a joke at all, I have the case completely apart and the 8" fan is literally face down on the motherboard blowing across the bulb and color wheel. Even like that, I have to take the cardboard shield loose from around the color wheel to promote better cross flow. That's incredibly risky cause the color wheel is intensely delicate and costs as much as a refurb whole unit. So, basically since this thing was 7 or 8 months old I've had to fight it to remain functional. Optoma customer support was no help and they want 160 dollars just to look at it and try to diagnose the problem at the repair facility. It's a known and documented problem with the public, but they don't choose to acknowledge it when you ask for help or try to get them to fix it for you.
Anyway, I've heard Epson has beyond incredible tech support and really stands behind their products. They recently released a 1080, bright, highly rated 3D projector that comes WITH 2 pair of 3D glasses that are quite expensive on their own, for only 1600 dollars. If I were you, I'd go that route. There are plenty of reviews from people on this site about that unit, I just can't recall the model number right now