I love Superformance . . . so much so that I have roughly 5 lbs. ............ For my .243 Win, I load ..............
It's always worth remembering that Hodgdon doesn't sell Superformance as an across the board / use in any apparently suitable application powder, rather one with limited applications.
Because this propellant is tailored for specific applications, the number of cartridges and bullets is limited, but where it works, it really works! (Hodgdon's website re the powder)
As 243 Win is one of Hodgdon's few listed cartridges for this powder, one would expect it'll perform at least reasonably well there.