I do not know what the difference in cost is between upgrading the IQ180 to the Trichromatic vs upgrading to the 3100. Whether the trichromatic offers any additional benefits to the technical camera user, above the marketed color differences between the two backs, probably depends on what lenses you use. If you have the Rodi's, I do not think you would notice any benefits in color cast. On the Schneiders, both the 35xl and 60xl, I do think there is a possibility you would notice
some improvement, but whether that is significant or not is tough to say. Is that non-committal enough??
I have four raw images on this link that are direct comparisons (two images and two associated LCC's):
https://spaces.hightail.com/space/HtAMyc7o9y
They are the last four on the list: 392, 395, 396 and 397. All are the 35xl. First two are the Trichromatic, last two the 3100.
In my opinion, those benefits are not dramatic. In fact, whatever I see in differences could simply be differences in exposure. I don't know that anyone has come up with a plausible reason why the Trichromatic should be any better than the 3100 in regards to lens color cast. Other than the filters being different, which will make the color different and the associated color cast render differently; but not necessarily
better or worse. The underlying sensor geometry has been unchanged, as far as I know.
Dave