DT is garbage, huge spread in velocity and the velocity claims are pretty well exaggerated. Not available in Canada unless you know someone who brought some over.
Stiff loads in calibers like 10mm often results in the slide opening too fast, so fast even that it impacts the velocity and volume of gas pushing the bullet. This makes huge spreads in velocity, in order of +/-100-200ft/s. Often solved by installing the stiffest main spring that will still allow the gun to cycle. Try it yourself, get a stock glock 20, a chrony, and 200gr 10mm bullets pushed with a powder load that would be supposed to send it at 1200ft/s. Make identical rounds, weight them all, every powder load, size everything perfectly, and chrony them.
You'll get insane spread and low velocity compared to what it should be.
Stick a spring that's 5-10lbs stiffer, and watch the same load perform as it should, or close. Stick a stiffer spring yet, until you get jams - then you know to use the one step down from the "so stiff it jams" spring. You can install a muzzle break to help as well, they pull on the barrel forwards as the recoil is trying to drive the whole thing backwards, and keep it in battery for a little bit longer.
I wouldn't blame DT for inconstant performance unless I saw it myself. All I hear from the revolver or rifle ammo is good stuff, so unless they royally messed up on all their autoloader calibers, I think it's just people not knowing that you can load it hotter than the pistol can "take" (not as in explode, unless you're way out of SAAMI specs, and these loads are on the edge, but as in so hot loads that it drives the pistol out of battery before the bullet is far enough from the barrel - remember, the gasses are pushing on the round up to a foot past the barrel, and you can seriously have the action opening and gasses escaping from the breech even before the round is out of the barrel.)