I have the HW50 at home AND the Little brother of the hd83 (the optoma hd33).
The optoma hd33 just smokes the HW50 concerning the 3D: no ghosting AND no flickering--> AND THEREFORE NO VISUAL FATIGUE!
(the HW50ES is just brighter but it's just not enough).
For 2D, the HW50ES will have better black than the hd83 and better on-off contrast. Still the ansi contrast will be on the hd83 side.
THe HW50 will also be a lot quiter.
Hopes that help!