@Gareth ... Cool that your using HeightMap and your paint idea is good. Although I personally would never use the paint option and here's why. I typically have multiple height ranges on a map and for the most part, the different heights represent different textures as well, so an all encompassing paint tool would literally have me painting over areas that I do not want to paint over. As far as using the option for general slam dunk maps, it would be quick and easy. But again the time it takes to paint areas (and at the same time, become more familiar with the map) is not worth the time to find out I painted areas I did not want too. I'll say again, good idea.
On a lighter subject of HeightMaps, I am getting close to releasing the official grey scale spectrum (to the members of this forum only) that literally carves the maps perfectly. Each grey has a specific cut height and depending how the highs and lows are valued you get better than great representation. ATM it consists of a 64 grey pallet with each shade contouring a 2 step height value. I will also provide my opinion as to the editor that works the best with least amount of mumbo jumbo.
First tip: Always edit in pixels
Second tip: Keep it simple, the more shades you allow to shape, the less you map will represent.
Third tip: Do all the map editing in the grey scale image, then import. If you need the further edit you map, try to edit the image first and re import. Remember, It takes minutes to edit your image and import compared to hours of shaping and then you realize it was a waist of time...
Lots of trials and errors... that's all