I haven't shot that many Dianas. But on the ones tried with the T01 trigger, including my little 24D, I've always found the unit very usable and predictable too.
Excellent result on the rifle, Mick.
As Jon says, do try and get yourself some of the lighter variety JSB made pellets for springer power testing / setting up. Would be handy for this and other projects. I'm not a fan of most of their fodder myself, as I detect that you're also not attracted, and the prices can be off-putting, but they most certainly come in handy for testing. To be fair, though, on a couple of my rifles tested, our trusty Hobby still pipped the lighter JSB RS and Express variants.