Not much to add to the replay verification thing.
If you're asked to provide a replay and you can't, your time will become 'unofficial'. That's no big issue.
It'll become one if you provide fast times every week and can't prove them. In that case, save all your replays so that you can provide all of them when you eventually have a replay device. That's what happened to fasj a few weeks ago, and all his replays were OK.
Replays are required, not because we think everybody's a cheater. That exactly the opposite. Replays are required because that's the best way for the middle and the bottom of the pack to improve their skill by finding better racing lines, different braking points, etc.
There's nothing to win here except other racers' respect, consideration and perhaps friendship. That's why there are no cheaters here, and when one comes, he doesn't stay long.
Now concerning the concrete part, I checked and its true that it could possibly be used to widen the line when entering the last corner and perhaps exit faster.
But the corner exit is rather narrow and you need a damn good line to carry your speed all the way to the finish line.
I doubt many of us would risk a wall touch (pretty close when the all 4 wheels are on the concrete) or a wide exit on the grass which would totally waste a 7-min lap.
Yet, I agree with Kent that using it to save a tenth of a second would be IMHO against the spirit of the rules : concrete parts are tolerated this week because the combo is the tougher we've had in the GT4 WRS and we want to give all drivers a chance to run a clean lap without too much frustration.
To make it short : I said "all concrete parts are part of the track" and if I change my mind for this specific part, someone will come with a question about the inside of the karrussel, then someone else with a question about another part and so on. So,
that concrete slab is part of the track[/I] and if you succeed in winning 0.1 there, then thumbs up.
I had another session tonight (30 minutes), and still no clean lap. I can now run a clean T6 but I don't know the turns between T6 and T8 enough and constantly lose the car there. 3 evenings left 
