I like to mix when doing Pulled pork.
I find the picnic slightly sweeter and more tender
The butts have a little more body to the meat. It makes a great combo.
However and as cfarmer posted. I have been doing more picnics also, because I catch them on sale sometimes for .99 a pound.
The yield is a little less on the picnics but they are more than 50% cheaper when I catch the picnics on sale.