Picnic roasts like that were the second cook I tried on my smoker when I got it two years ago (ribs were first). I saw a sale circular from a local grocer, and didn't understand yet exactly what a pork butt/shoulder was, and thought this was what I was looking for to do pulled pork, even as small as they were. Turned out they weren't so appreciably different from actual shoulders that they caused any problems for us. We kept them separate, and used the opportunity to experiment with a couple of different rubs to see which we preferred. Everything about the cook was just the same as for a shoulder - same prep, same temperature, same target IT (203 +/-), and they came out fine. If I recall they worked out pretty close to 1.5 hours/pound, where all my subsequent full shoulder cooks have been closer to 2 hours/pound. But to be honest, cooking times have been so all-over-the-map for me, I give myself at least a couple of hours cushion when I plan - the meat can always be kept wrapped in a cooler for that long if it gets done early.