Double baffling causes an additional increase in consistency. Hence the Dillon add-on. It depends on the powder, but flake pistol powders especially seem to benefit.
I'm not sure what the concerns with emptying the baffles to change powder is? The baffles have cutouts to pass the powder, and it pours back out through them pretty easily. It is just a bit slower than pouring without them. You will catch a charge or two's worth of powder in the corners of the baffles with the hopper inverted, but you just right the measure and tap it a few times to shake that down, then dispense that last little bit into a cup to clear it out.
If you followed the link in Shoney's first post above, below his post I have one with a link to my PDF file of powder baffle templates and instructions for making them. You can also download it at my file repository,
http://drop.io/unclenick. It saves you having to figure the ellipse to follow the tube diameter when bent.