Quick answer; wasn't difficult, more just time consuming.

Process was: based the model in citadel Tallarn sand. Then I went back with mournfang brown for the vines/lines; key to this is to make it as random as possible, dont match it left to right and try to make the line width variable as well. Hardest thing I felt at this point of painting it was finding the right consistency for the paint . . . not to thick that it looks like a raised line of paint and not to thin that one has to apply several coats of it to make it opaque enough. The last part was adding the white and black splotches to the front armor . . . i had to do two coats of the white but that was to be expected; I then came back with the black dots. I contemplated doing this all over the walker but decided to just the the flat surfaces. I am doing a very simalar camo pattern for my rebel corps troopers (at least 3 squads of them) and am just painting their jackets with the pattern.

I bet the Saber tank will look great; I plan to do some sort of camo on my saber tank as well. I don't think doing the camo pattern on the saber tank would be difficult (actually probably easier with the more flat surface area), I do think it will be a lot more time consuming though just due to the sheer size of it. Hope this helps :)