The 7mm STW was an example of classic special advocacy by Layne Simpson. He liked to compare the STW, loaded to the nuts, in a 28 inch barrel, to the most anaemic factory 7mm Rem mag ammo he could find, fired in a 24 inch barrel, to demonstrate the superiority of his STW. I was annoyed by the hype and flat refused to chamber them for the first couple of years. Finally, it occurred to me that I was only hurting my own bottom line so I bought a reamer and went to work. I think I chambered or re-chambered about 35 of them the first year then fifteen or so the next. Within three or four years, the market seemed to have been largely filled and I was, once again chambering more 280's than STW's.
From the same barrel, the 7mm Remington will do about 3150 or so with 160's while the STW will manage close to 3250 at the same pressures. If 100 fps means a lot to you, then the STW is the cartridge for you.
The place where the STW really shines is in it's ability to use real slow powders with lighter bullets. With some powders, the 7mm Rem may not have enough capacity to reach max pressures with a case full. Here, the STW's extra capacity pays off and one can reach some very impressive velocities with bullets from 120 to 140 grains.