I have a GLOCK 17 and purchased the LWD threaded barrel (stainless) to attach my Evo-9. Works great and I absolutely can't complain about the reliability.
Earlier threads in the SilencerTalk forum - the primary forum - have indicated that it could conceivably be beneficial to use a left-hand thread so that the suppressor has less of an inclination to unscrew. I wondered at that time - and mabye even posted to that effect - why not just have the barrel twist differ instead of monkeying around with the threads which would then lead to problems attaching a suppressor?
Well my LWD barrel is already set that way. In comparing its internal twist, it appears to be visually the same as my GLOCK OEM barrel, with the exception that it twists in the opposite direction. It appears that whatever spin the bullet would impart to the air and suppressor to unscrew it have now been set to tighten instead. That said, I must still reach up and check the tightness of the connection on my Evo-9 every magazine or so (17 shots).
The conclusion to be gained from this is that the ordinary vibrations associated with shooting are likely the key culprit with the loosening of a threaded suppressor. I suppose its possible that the different twist direction could offer a minor amount of aid or hinderence, but it would be miniscule.
Therefore, if you are considering going the very awkward route of having your barrel custom threaded to a left-hand pitch to avoid having to tighten the barrel, then DON'T. It just won't matter, and you'll be shouldering non-beneficial time and expense.
Lone Wolf Distributer threaded barrel
Lone Wolf Distributer threaded barrel
I read that it's douche to list your guns here, so I stopped that.