Maybe someone has already said this. I didn't read all of the replies.
Commercial loadings for the .44 Mag. are often for hunting ... i.e. dropping a thick boar hog or other nasty/evil monster animal. For self defense against human felons / nut-cases, the hunting rounds could be over-penetrative -- actually, very much so. Thus, there are now commercial loadings for the .44 Special tailored to the purpose of self defense. The .44 Mag case has lots of volume ... maybe too much so for light loads. The .44 Special case is likely more conducive to accurate/effective loads than the .44 Mag case.
I'm no reloader, so those who reload these cartridges can better speak to the topic of case capacity issues ... effects on accuracy, effects on velocity deviations, pressure levels, ... all of that. I do know that having a whole lot of empty case can result in negative effects. Is the powder up against the bullet for one shot, then back against the primer for the next shot, ... ? In rifle cartridges, loading light can cause over-pressures which is counter-intuitive yet oh too true / dangerously true.
.