I am a Claydot and International Clays user....BUT....
Even though Promo has a rep as a dirty powder, just about all powders will burn fairly clean if the pressures are kept up above 9500 psi (including Promo). Below 8500 psi or so and they all are real nasty. It will be hard to tell the difference between any of the major brands if you will keep this in mind.
p.s. In my neck of the woods Claydot is like 7 bucks more per 8 lb jug than Promo and my Beretta 391 loves it.