I was wrong about the 4G being designed for gut/poly.
I tried it out today using Pacific Gut mains. The 4G absorbs spin! I got less spin from the 4G 16L than I did from Black Magic 17, Hurricane Tour 17, BHBR 16, and ALU Power. The performance didn't drop after 2 hours, though. The problem is that the performance was never high in the first place.
Luxilon 4G will be the new Windows Vista of tennis strings. Overpriced piece of crap!!!