At a glance, it looks to me like the bottleneck (the limit to how much heat can be removed) is the size/noise of the exhaust fans, not the thermal interface area between heatsink and heatsource. Meaning that I don't really expect a repaste will do much unless ASUS used really cheap goop in the factory (which seems doubtful, considering how much effort they put into engineering the rest of the cooling solution).
I wish you luck and hope the best for your repaste. I just don't think it'll give you enough of a temp drop (which equals performance lift) on your gaming laptop to really be worth the effort.
It would be interesting to see your temp and fps benchmarks before and after.