Just tried no flag rules on the dedi server with the following results:
1. You can jump the start. My first lap in the 914, sitting in the next seat over from the wheel and right foot braking, was a 1:30.
Not really a problem with a rolling start though.
2. You can indeed cut all the corners you want. Not only that, but it correctly logs all laps. Woo!
3. You can speed in the pit lane. Not so good - although UKGTL doesn't normally use pit stops unless you've broken the car.
On balance I think we could sanction running with no flag rules in UKGTL. UKGTR Endurance will be a different conversation...