I can tell you this much about my results with H13 over the last five or six years, the 6s and 7s pattern VERY WELL with a JH choke and the HeviShot choke in my BGH and SX2. And they pattern well at much farther than I want to shoot.
The irregular shaped shot shouldn't be a concern as the loads pattern excellent resulting in dead birds, the shape thing makes no logical sense as we are all used to uniform round shot being needed to produce good patterns, but it is absolutely true.
Where are you seeing the price difference between the two loads? I looked in a couple of places and they are priced the same in 3 1/2" no matter if you want 5s, 6s or 7s.
Prices at the convention? No idea on that one either.