So, after lots of googling, Youtubing and general researching, I've ordered the cranks for the !x drivetrain swap on my boys' Trek using the Dore stuff from Wifeys' Aldi 29er. I was mucked around by a couple of bike shops, my LBS said it couldn't be done. Another one had some of the worst communication I've ever experienced and because of it Shimano Australia sold out of the bits I wanted before I could get them ordered. Dodgy online sellers didn't get a look in even though they were showing stock of the bits I wanted. I just couldn't do it.
Ended up ordering Truvativ Descendant Eagle DUB cranks, 170mm non boost, a DMR Blade 30t cahinring and SRAM DUB Bottom Bracket.
Got it all from Pushys.
Can't wait to get the swap done.
Cheers, Mike.