No lens shift for the Epson Home Cinema 3010, so mounting properly is critical if you don't want to have to use keystone correction (which does very slightly degrade the picture).
Let's talk about that for a second. I received an email or blog comment recently, asking "how bad is using keystone correction". I have an easy way to describe that for existing projector owners: Any softness caused by using keystone correction, is going to take away less from picture quality, than the compression being used on satellite and cable transmissions. So, while we cringe at the thought of using keystone correction, it's not going to do something drastic, like make a 1080p image seem as soft as a 720p one in terms of sharpness.
On Blu-ray disc, you should be able to see a slight difference between keystone on, and off. It will be harder to see on lower quality sources.
By definition the keystone correction compresses each line of data differently, but there never should be highly visible artifacts from today's keystone adjustment formulas