Mrmy, can you fill in the details of your system.
1) Where did you get your filters?
2) What Screen is that. The new Vutec Silverstar 3D-P is curved so hotspotting should be minimal, but of course it costs as much as both the HD33's combined. Using mamimum throw on the HD33's will help a little, but they don't have much zoom range.
3) How did you align the projectors without lens shift? Of course you tilt them, but how much keystone correction did you have to do, or was it close enough to just leave?
Your brightness looks really good for a linear filter system. Is a single HD33 in 3D crazy bright on that screen?