We must've been working on that image at about the same time, and you beat me to the posting. I used all six filters, which seems to tone down saturation a little bit without giving me anxieties about going down the slippery slope of manual adjustment. I also sharpened all six source images before combining them.

What I get has more saturation than your preferred versions, and I lean toward thinking that my method is (relatively) more accurate than your favorite 42%(?) reduction in saturation (but then, we're wading into the swamp of The True Color of Mars, and I've learned to not get too attached to any recipe). Another six-filter set the same sol provides an independent check:

The nice thing about this one is that the colors of the flag fell into place fairly closely without any manual intervention. There's a similar shade of adobe dusting the RAT, which I'd suppose is the same material dusting the rock.

I'm a little skeptical of desaturating as much as 42% because, at least in this case, it resulted in adjacent ground color that's a pure neutral grey. Of all the interesting colors we've seen around that site, the one I'm pretty sure we've never seen is grey. It's not that I'm claiming to know The Truth, but I think that the truth does lie somewhere between the extremes of heavy desaturation and the oversaturation we see with 3-color combinations.