Turns out that the two Berthoud saddles measure the same on the inside of the cantle/crescent part of the frame: 104mm. However, I found that on both of them, I sit just in front of the cantle, but on the overall-narrower one, there's not enough material to support me without hitting the "corners" of that part of the frame, and setback doesn't seem to help. Neither does a more aggressive position with the bars well below the saddle. I guess I've confirmed my suspicions of this saddle just not working for me!