Jony,
I hadn't expected to see this thread come to life again!

I gave up on GOKO as there hadn't been any development for several months and got no response to my queries, though I liked the low-cost combination of the G2Core software and Arduino Due, especially as there is a breakout board available to make connection to the machine easy.

I've only had a quick look at GrblGru and it is still very much in development but the 106 page manual looks comprehensive and far more detailed than the usual support for a new piece of software.