I currently have a Sanyo plv70 in a non-light controlled room. Screen (106")is 14 feet maximum from pj due to physical limitations. Seating is 12' from screen. Sources are Directv (hd) and dvds (hd-dvd) as well as sd material. How much difference (better?) would the sp777 or the hd81 lv be? Is it worth the upgrade?