Yup, I'm on a 10mb line and also have netflix (US version) running on my WD player. In my experience, I would typically only get 384-480p streams with AH capped account. With testing on VOX (my current provider) and WA, quality was typically a bit higher, mainly 480p but would jump to 720p periodically.
On an aside, changing to the UK version of Netflix via Unotelly's dynamo setting made a huge difference to quality. Hitting 720-1080 streams easily which I would never get on the US version, regardless of which ISP I'm on. Content is a bit different but I prefer the UK version in any event