In 2011 they held a direct, live, side-by-side comparison of 15/70 IMAX film vs 4K DLP at Moody Gardens in Galveston, TX. The general consensus among the industry professionals was that the 4K image was superior. I can only imagine that Imax’s laser system is superior to that Barco DLP projector. So I don’t doubt that by standardized metrics the Laser system is technically superior to the film system.
But it doesn’t change the fact that imax film is flipping amazing an can resolve FAR more detail than even the best digital mediums. Whether that detail makes it to the projected image is more debatable I guess. And resolution is far from the end-all be-all of image quality. Brightness, contrast, and color reproduction are all just as important as resolution.