Hi
It's not been designed for lower latency, and if anything it's probably worse than VDSL as G.Fast uses Time division multiplexing, this means it's really a half duplex connection (it can't send and receive at the same time), so the line is constantly switching direction, so when you send some data, the modem has to wait for it's turn to talk, then wait for it's turn to receive, adding extra latency.
G.Fast is a rubbish technology really, reach is poor, and it interferes with FM radio so has to have all sorts of power reductions applied over specific frequencies, further reducing reach.
Regards
Phil