I think the reason that the Nouvelle Piste is short is down to it being on a spur.
Measuring the Arc course on Google Earth shows it to be the advertised distance. All other distances on the Grande Piste and Moyenne Piste should also be as advertised although there's no obvious point of reference to measure them from.
Regarding the Racing Post standards... personally I think they're poor.
Firstly, they make no allowance for whether the race was run on the Moyenne Piste or Grande Piste (or the Piste Ronde for that matter). Indeed if you went solely by the info on the RP site you wouldn't even know there was multiple tracks there!
Secondly, lets just take a look at the standards for the distances between 1m and 1m4f. Let's assume that the RP standards intend to reflect the Grande Piste (with the possible exception of 9f, which might be only on the Moyenne Piste), and let's ignore the extra inaccuracies brought in by using the imperial measurements rather than the metric ones that the course uses. Remember, all these distances are subsets of each other; they're run on the same piece of track:
Yards : Seconds
1760 : 97.4
1870 : 104
1980 : 110.5
2035 : 113
2145 : 119
2200 : 123.9
2310 : 130
2420 : 137
2640 : 151.5
Now, if we graph these figures we get:
Now that looks a bit odd to me. On the same piece of track, where the topography isn't dramatic, I'd expect the above relationship to be a little more uniform.
Another way of graphing it is not to look at the distance vs the standard time, but at the distance vs the average speed required to meet the standard time.
Obviously you wouldn't expect the relationship to be linear, as an 8f race would be run at a higher relative speed to a 12f race.
Here's the data:
Yards : Miles per hour
1760 : 36.96
1870 : 36.78
1980 : 36.65
2035 : 36.84
2145 : 36.87
2200 : 36.32
2310 : 36.35
2420 : 36.13
2640 : 35.64
The eagle-eyed amongst you won't need the graph, but here it is anyway:
Does it make sense to anyone why the average speed required to meet the standard actually goes up no less than 3 times despite the distance increasing? Am I wrong about the topography? Is there a big downhill bit exclusive only to those distances or something?!? Or are the standard times just, well, slapdash? Given that only 4 of the 9 are precise to less than a second, I know which one I think it is...