Mogwai according to the info I received over the past year from gunsmiths and gun manufactures, pressures in shot guns are much lower than those in rifles. Therefore recoil is only about 10-15% verse's 40-50% in a rifle. The main thing it does is prevent muzzle rise. Tar-Hunt put them on their guns for that purpose along with the fact that it helped their sabots separate sooner.
I'd look into how short you want to go. They say 23 inches seems to be the optimum barrel length for powder burn and slug stabilization. However there is some controversy on how long it actually takes the powder to completely burn in a shot gun barrel. Remington told me it's done in 15-18 inches, and some gunsmiths have said 20-23 inches. So you may want to do a little research before you wack that thing down to far.