imo you will never get a realistic result in GED. and I found GED instable, texture quantity is limited to 3, which is simply not enough.

in Unity it is very cool, I mean the 3rd party extension that can be downloaded separately, I got a lot of inspiration from it when I designed terrain deformation in my editor. in future what I want to complete is implementing terrain erosion, and height and slope based auto texturing. but it will probably require to make/obtain a good terrain shader instead of the currently used terraintex ffe (its main advantages are unlimited textures, ease of use, and compatibility with all engine editions).

in 3dgs it is the best to use L3DT, because of its very easy usage and professional results. or try PnP Terrain Creator, it exports hmp in compatible format with the modified terraintex ffe I use in my editor (based on MQ32's idea, posted in Future section). both tools are free.

the terrain deformation in my editor is rather for post-processing ready terrains to fine tune surface due to the actual gameplay requirements. the result can be saved as hmp or in an own format, but modified textures can be saved only as external image files, I was unable to solve it to be saved as hmp.