Here in MA we are required by the MEC (MA Elec Code) to do the diagonal support thing with or without attachment to the grid itself.
We use the 12 AWG ceiling wire and we own all the tools a ceiling guy does, ramset on a pole, 15' tek screw drivers etc along with an open acount at a cieling supply place.
We did have an inspector refuse the 12 AWG steel wire and had us use 12 AWG Jack chain.
This is foolish as a 12 steel ceiling wire will support my weight a 12 jack chain will not come close to holding me up.
Had to re support almost 1000 fixtures, GRRRRRR!
It turned out to be an local ordnance that we could not get out of.