1gig broadband virgin media

Any improvement of latency with 3.1 is well within the usual variation between different connections, and at more or less busy times of day.

If you really want the minimum latency for games, don't choose DOCSIS. It wasn't designed for gaming. 

Gamesters do like to ignore that on a given network higher speed usually brings higher latency.

Using a Hub 3 on RFoG latency is typically 15ms.
Less than 1/60 of a second.
Less than 1 frame of a 1080p60 screen rate.

When thinking about latency, focus on one eye blink is around 125ms. 
For 1/8 of a second you can not see the screen every time you blink.
You miss 8 frames at 1080p60 screen rate or 16 frames at 1080p120.