colour over time overhaul

[cgdvs]

It's not clear what the issue is - also you don't need a Custom Properties operator anymore...everything can be done within a Mapping operator:

Mapping operator (mode: "from value"). Set value to 1, set interpolation to frames (curve interpolation) and however many frames (duration) you want....this will interpolate the UVW value from 0 to 1 over the specified number of frames.

Then you use a Gradient Ramp in your material, set it to the same channel as the data in your mapping operator and the colors will interpolate. Gradient ramp should be compatible with all materials/renderers.

Not sure how to make it any simpler than that, while also offering the same amount of control and being compatible with all materials/renderers...

I believe what he means is this: he wants tyFlow particles to have an internal particle material attribute. For example, to make particles change color based on their age, you would simply create a "tyFlow Material Property" operator. In the operator's attribute list, select the age attribute, adjust the min and max values on either side, and there would be a gradient below for custom color setup, and so on. Changes to these settings can be previewed on particles in real time.
I think this is what this user is asking for. He just wants to simplify the workflow, so desired effects can be achieved by tweaking just a few parameters.