The only way I see a legitimate reason for them to be pissed, is if their cars weren't capable of 10.9 in the first place, and there is no solid proof that this was the case.
The newer cars having more power is not grounds for the early P90DL people to be pissed unless their cars were incapable of running 10.9 in the first place, and that much has not been solidly established.
I agree being pissed over the greater power of the latest p90dls isn't reasonable. But I can see where someone might be concerned about the capabilities of the original p90dls.
I know the small number of samples that are available from a very noisy data set do little to answer the question.
If you look at TRC's recent time slips, his times range over 0.1s (10.8 to 10.9). This is for the exact same car and driver at the same track under the same conditions. I assume he knows to stage as shallow as possible. His better elapsed times come at later times in the day. Is he charging between runs? We don't know. So I agree we can't use the data we have to answer the question. But it's looking tough.
The relationship between elapsed time and power is similar to the one for weight.
et2 = et1 * cube root of (power1 / power2). Using TRC's data and an early P90DL power of 456KW:
10.8 sec times the cube root of (500Kw / 456Kw) equals 11.14 sec. As for weight this number isn't exact. The power of the new cars varies around 500Kw and the older ones vary around 456. So I wouldn't say that this makes it impossible, but it's by no means certain. This is with a light car and driver, too.
And here's why I'm only beginning to see their point. I'm still not certain about using the relative max powers here. I'd like to see more detail about the voltage and current during acceleration. I don't see the advantage to tesla in saying that the p85dl conversions would under perform the original p90dls if in fact they were identical.
I'm sure this has already been argued endlessly, so let me have it.
So again, I agree we can't be certain one way or the other, but I don't begrudge them their doubts. And, of course, you shouldn't let anything I've said prevent the good fight.