As big of a fan of the 7mm STW as I am, I will say this... If that rifle is not offered factory in the STW, but it is being offered in the .28 Nosler, go for the Nosler. The reason being, the .28 Nosler and the 7mm STW are ballistic twins, and you will get the same performance from both of them all the way down the line. So, in order to keep from buying a new rifle and then modifying it, you could always just go the .28 Nosler route and save a lot of time and money.
Also, the 7mm RemMag will do just about everything the 7mm STW and .28 Nosler will do, just a bit slower, and a few hundred less yards of kill range...But it will still kill at well over the 1,000 yard mark.