i dont know bout that, but my LTD licensed FR can stayed tuned for weeks,
the trick is just like u said, u need to stretch the new strings before u locked it..

for me after installing new strings, i will not locked the nut straight away,
id left the nut unlock and played the guitar as usual for 2,3 days, that is to let the strings stretch,
then will i retune and locked the nut, after that it will stayed tuned for weeks,
even if it slightly out of tuned after weeks of abuse, i still can use the fine tuner to tune it back to pitch..

yeah, ive heard about it and still experimenting which string is best for my axe setup,
so far, the winner is daddario .10-.46,
currently im using ZW Sign strings, a bit disappointed with the tone tho, not my taste,
well there are lots of strings that i havent tried yet, experiment continue ..