Well, just to add to the confusion..... we watched the first half of Inland Empire on the A2 and then finished it the other night using the PS3 just because it was already on from earlier gaming use. I felt the PQ was better coming from the Toshy A2 than the PS3. Now, this movie was shot with what is essentially a home video camera and David Lynch uses some interesting shots so it may not be the best test disc.
But, from my very small sampling I would use my A2 to watch SD discs before the PS3. Some of that might be because the PS3 does enough "work" for us so it gets a "breather" or a "day off" on SD movie night.