I'd imagine some experimenting will need to be done with it to find pressure limits, as the Hodgdon site is showing performance specs oddly similar to .44mag, and they don't show pressure. But with like 1/3 more powder capacity, there should be a pretty notable increase in performance. Out of a rifle, I'd expect a 240 at 2000+fps at least, given a .44mag can do 1800+ with the same bullet weight. That seems more like .454Casull performance than .444Marlin, though (not that it still isn't a big leap though!).
*edit*
There is a load on handloads.com showing a 315gr bullet doing 1972fps out of a 22" Handi. So, a 240gr bullet should easily be capable of 2100+fps at the same pressures. Also, there is a 360gr load @ about 1900fps and the description says "20fps slower than the 444marlin load." These two loads are about 100fps slower than something Buffalo Bore would put out, and they load about as hot as any commercial loader I've seen. So, maybe it really is approaching .444 Marlin performance!