I like that effect racer-x.
Maybe you will like G'MIC>Testing>Naggobot>Dodge sketch (with color on)

You can combine layers with more color with the result from "Dodge sketch" filter.
Also there is Iain Fergussons "Pyramid processing" filter: G'MIC>Testing>Iain fergusson>Pyramid processing
That filter does't process contrast, gamma satuaration etcetera (as in the filter you described above, from Michael Vinther
http://meesoft.logicnet.dk/ ), so you have to do that kind of filtering after or before the editing with the "Pyramid processing" filter.
And there is the "Tone enhance" filter: G'MIC>Details>Tone enhance (by Garagecoder)
You can get much color with the "DCP dehaze" filter: G'MIC>Details>DCP dehaze

After that you can smooth the result with a smoothing/blurring filter you prefer.
Little playing here:
