Of course! Mea Culpa -- thats why i always preferred VUDU rather than amazon!
In vudu we have some proper speed test and can easy see what quality we get. Usually I got HDX - thus full HD and 5.1 sound.
In fact I am so accustomed to this lovely HDX on VUDU, I just started to rent videos on Amazon in HD, not thinking a bit to check if amazon really played in HD / 5.1.
So, now back to vudu. See if things get better. My asus rt-n16 should be here in a few days, hope I can get some % extra speed :-)