I recently upgraded to a 2.6 gain screen and calculated the FL for my two projectors.
Mitsubishi HC3800: Guessing the lamp has dimmed to 75% and 1.5 gain from my seating position I get about 30 FL in best mode.
Acer H5360BD: Fresh lamp, 2.5 gain from my seating position, I get 67 FL in 3D mode.
I actually run both in eco mode, so I'm not actually getting that much. In a dark room, I think the brightness is for both projectors looks great and doesn't bother me at all. Of course for the Acer that 67 FL gets cut down significantly by the 3D glasses, and the result is vibrant, appropriately bright 3D, much better than when I used a 1.0 gain screen.
So my opinion is that no, 22 FL will not be too bright. In fact if you use the HD3300 for 3D, you might find the brightness lacking, though probably acceptable.