I run this powder in a 22/250 and 6x47 Lapua with 55 and 75 grain bullets respectively. In both cartridges it gets top velocities at lower pressures than suitable ADI powders and as the CFE part states, it does reduce copper fouling. For 243 with 75 grainers i see no reason it wouldn't work well.
I use it as well, bought 20lbs plus before Winshitter discontinued supply, currently using it in my 308, 358 and 6mm ARC for lighter projectile. A bit temp sensitive but match it to the right application and its a cracking powder