i actually have both a3 and dv 600, the a3 (upscales to 1080i) and the dv600 (upscales to 1080p), but i upscale only to 720p since my lcd is only 720p capable. and imho, i like the upscaling of the hd-a3, but since my collection are mostly r3 dvds, i use my dv600 more often because the a3 can only read r1 dvds, i'm not sure the a3 can be region freed yet (i might be wrong).
bro i think our fellow pdvd friend juancho was succesful "region freeing" the a2. you might wanna try what he did. i have the d3. hope it will work.
