The first thing to do is to optimize contrast and black levels in the projector itself, as you will do by using SMART and CC filters. Then it's question of how much screen gain is necessary to achieve the right balance between black levels and overall brightness. Gray screens, like ND filters are a great idea for projectors like an un-tweaked 10HT with mediocre black levels, or some of the newer super-bright, projectors (PLV-60) that put out greater than1000 Lumens.
With Cinema black on and with a CC filter in place, my feeling is that a white matte screen with no gain is just about right for the 10HT (with a 102" diagonal). I'm not sure I would want to give up any more brightness to get even better blacks.
Steve