I've never used WAP, but have used a fair amount of Silhouette.
If you are looking for a powder to barely make Powerfactor for competition, this isn't the powder you want. In my experience, there was quite a bit of unburnt powder in the lower end of the load window, but it cleaned up nicely in the upper half. If you like to shoot full tilt 9mm loads, this is a fantastic powder. Ramshot lists +P data for this powder, which can achieve 1,200 fps with a 124 grain bullet. This is also a powder used for 9mm major in custom built, compensated guns.
Personally, I really like the powder. It meters like a dream. The Ramshot data was pretty close with lead bullets, IIRC. It's also great in .40 S&W.