Yeah, you keep talking about getting the *current* difficulty from whattomine while I keep saying I am using the *average difficulty for 24h* from minethecoin; very different, those two.
Now, there is one potential problem with using the average difficulty from minethecoin and applying it to the pool: minethecoin is likely performing a moving average for all of the blocks found by all of the pools for the past 24 hours, whereas any given pool will only find a fraction of the total blocks found in a 24 hour period. But I anticipated this issue and it is one of the reasons why I chose the official Trezarcoin pool to do my test and ran the test for 24 hours - again, that allows me to use the average difficulty value from minethecoin and it helps reduce the effects of wild variations in pool luck and/or of the difficulty of the blocks the pool does find.
I already agreed that running the test concurrently with identical hardware on the same pool, just different wallet addresses, would be a better test, but I don't think that automatically means my methodology is worthless.