2p worth
personal i run both, i like the grillz for marshalling and playing. tried and tested good gogs.
the i4, when i recieved it didn't look as well constructed as the grillz or i3. but after training a couple of times i can say they are really good gogs.
very light, massive field of view, small profile and real quick lense change.
i would say try them.
the only thing i worry about with the i4s is the foam construction and how long it will last but give me six months i'll tell ya.
woody