After a lot of trial and errors I finally came up with a pleasing "Rock" object population.
(http://i.imgur.com/cDbtcTP.png)
Unique Variations is at 30 for rendering, probably best to crank that to the default 100. The mosses mask is based on a image shader (provided; and yes I forgot to invert it lol) of some contrasted moss turned into a matte, so don't forget save that and replace the image mask for the Moss Controller in the rock object.
Thanks.
No problem m8. Let us see what ya make if you do end up using it for anything! Especially cause I can't even see it fully rendered yet! xD