Here are some pics I took of the two seats on my Xstream, not moving the seatclamp. I put the SM seat on, and could get it to pinhole #10 before bottoming out on the struts -- so I got CLOSE to the same seatback angle.
However, as mentioned before, the 2009 SM seat puts you about 2" higher than the Hoagie does (which they may have changed since). I drew the line where you would theoretically "bottom out", so to speak
, and had the marked box behind as a height reference.
This difference in height is what contributes to your knees being a bit higher, regarding handlebar clearance.
Hip "open" angle is about 145 degrees in both situations. I moved the baseline up to intersect approximately where the hip joint would be in both cases -- so I'm not sure a SM seat is going to help your hip discomfort issue if it's related to angle.
Again, however, the SM seat is not going to give you the same upper back support in "push" mode -- the Hoagie top angles in at about 35-40 degrees vs. the back, and the SM seat only angles in at about 20 degrees - plus, it's mesh, not steel frame.
But it's still worth trying if you can get over to Hays! Riding comfort is a very subjective thing, no?