I can't see what the issue of the "true" colour of Mars is so important. 2-5-6 and 4-5-6 combination produce a landscape indistinguishable to the human eye. Using L2 (near IR) rather than L4 (red) for the red channel increases clarity slightly, which is good.

The trouble is, most of those who get obsessed about the colour of Mars are skirting woo-woo territory. There is a spectrum here, but fairly soon most of those who complain about the true colour move on to saying NASA is hiding the true colour, and that if only the true colour were released we would see blue sky, green veegtation and lakes of open water.

Jon