I own a 30mm Cadman Tuxedo it is a great brush, when I first got it I was concerned it would be too big but the Loft on mine is set to about 55mm so it isn't a brush with a big splay, but it feels amazing on the face very luxurious if that makes any sense ! It eats soaps too.
I have never used the Simpson brush so can't give a direct comparison but I believe they too don't splay so much.
I like the knot so much I just replaced the knots in a 24mm and 26mm brush with the same Knot and it is a great knot in the smaller sizes too.