never used the GC mc, used inital over Zirconia like it alot good results, nice handeling and little shrinkage- but you still have to layer- you are thinking of the GC initial IQ- havent tried it- i would think they are pretty much the same
the In-Line 1 is compatable with the standard inline, i put the inline occusal dentin orange down in my fossa, to give it a little pop
Greg Amendola MDT