In my view the projector resolution isn't that important, all it does is displays the patterns. Getting the sharpest projection is more important imo because even if the projector display 720p, the camera only see it as a blot of light, not the pixel on the projector.
With my tinkering id say a higher resolution will get better details but at the price of size. Going from a 240mm to a 120mm scale shows how much details difference there is the closer the camera is to the subject