I want to add a medium telephoto lens for candid street photos at a distance of 35-50ft, I am keen on the 200mm f/2.8, however have to keep in mind my camera a 400D - would it be too long? cant see myself shooting birds etc or football, soccer. Prefer a fast prime, any advice? :/
Personally, I would suspect that a 320mm EFL would be too long for street/candid photography, but I have found a few people who love a particular 300mm EFL prime for it, so you may be on the right track.
If I was using a Canon, I'd probably be more tempted by the 135 f/2. In this case I think the shorter lens may be a little more versatile, but it all comes down to shooting styles and the subject that you like. They're both very well regarded, so it's hard to go wrong.
Pat - the 200 2.8 is a wonderful lens. Enjoy.