Be aware that the lead Dev of GTCE is a very toxic Douchebag, and that I am pretty sure that he did (and then undid) some illegal Stuff to the License of GTCE, as changing the License of an OpenSource Project is usually less than legal without the permissions of all Authors.
I will not do anything against it, as I hate all that Drama and Legal bullshit, but be aware that this is a rather Shady Version of GregTech.