Hmm... I don't doubt that pressed media runs the same on both boxes when the chip is disabled. How about you run a pressed (i.e. not a backup) disc on both boxes with the modchip enabled. All other things being the same (we can discount the Hynix since it runs "pretty much" the same on both boxes with the pressed media in the same optical drive), any discrepancy running pressed discs between the two boxes with the chips enabled should indicate a discrepancy between the performances of the hacked bioses.
That'd be an interesting test, at the very least.
Xecuter did again recently state they're working on an X2 bios, so we'll see when that happens. I know they don't like giving dates (you should see all the pandemonium anticipation of the latest X3 bios release is causing on their forums) but I'm sure when the new 1.6 X2 bios comes out it'll be hands-down the best (excepting perhaps the X3 bios).