What about femur length? If you have had a fit test done, that will be one of the major variables in determining ST angle regardless if you are on a touring bike or road bike. It doesn't make a lot of sense to design a touring bike w/ a slacker ST angle assuming the rider's femur is long enough to make this work. To say that a slack ST angle means the rider will be more upright is not correct since this depends on HT angle and TT length as well (and visa versa).

I have a steeper ST angle on my touring bike than on my road bike yet I am more upright on my touring bike.

Check out this article. It gives a brief but clear explanation of the effects of ST angle. http://www.billbostoncycles.com/seat_tube_angle.htm

People have explained some characteristics of different angles but regarding two same purpose bikes of the same size w/ different angles? You probably have to ask each builder.