I am preparing base maps for a huge area in the mountains of Telemark, Norway. (About 115 km^2)
The main problem with OL Laser for such a big area is that the source data consists of 67 separate LAS files, so it takes days to process them all manually. :-(
(I am talking to the OL Laser author about adding a batch mode, and/or a command line interface.)
Yesterday I used the open source LAStools utilities to process all the files at once, first generating a vegetation height map, then converting that to a grey-scale image (130 Mpixel!) image.
I then used Photoshop (but many other programs would have done the same job) to first convert the grey scale image to an indexed format, then replaced the palette with a custom set similar to your setup, mapping various heights to different (mostly) green colors, before converting back to RGB jpeg.
Total processing time was less than 30 min, with only 5 min of manual adjustments.
Now I want to look into a more intelligent conversion process, looking not just at maximum canopy height but also the density of any intermediate returns (between ground and first return).