That's a beautiful horse, I love horses with blue eyes. And yes, I agree the flank isn't supposed to be tight. I think the guy with Master Saddles idea was that the wider the cinch, when it did have to work it puts on less pressure. Kind of like a seatbelt as wide as a string, or a traditional size, on is going to hurt more if it "snaps" into place, like when roping or riding down a hill at speed, or jumping.
And I do think it does complete the look of the saddle, trying to convince my wife to use one. She got thrown a few monthes back and when it happened I'd swear I saw the saddle go straight up, which a flank would have prevented. But, I guess to each his/her own.
Thanx for the input