I've got an Optoma HD70 and I've got a CyberPower UPS that is rated at 230 watts, 425va. If I read the specs on the HD70 right it uses 250 watts, which is around 440va. Now I'm no electrician but that doesn't sound like a good match. My questions is, will my UPS simply not handle the HD70 at all or will it work but I should expect short battery run times? If I use this UPS will I ruin/damage my HD70?

That should be fine. I use one with less watts...I think like 180. And that should give me probably around 30 - 40 seconds to properly power down the pj, in the event of a power failure.

I doubt you will ruin it.

I've always read a good rule of thumb is to have a UPS that doubles the wattage of the PJ.

Then again, that is probably overkill if you are just using a UPS to perform the usual shutdown should you take a power hit. I'm guessing what you have will be fine. However keep in mind, with age UPS batteries don't hold up very well, and in a couple years, your UPS may not be sufficient. Just a guess though.

If your PJ needs 250 watts and your battery can only supply 230 watts, you are subjecting it to a brown-out. It may work but that is not what you put a battery on the PJ for. They are cheap, get one with twice or three times the wattage and make sure it is line interactive.