I do the same sort of 6 and 6 that Elbone talked about, but I usually start my shoulder in the oven and finish it off on smoke and charcoal.
Cool idea! I can't think of any reason that wouldn't work perfectly. Plus you can time it so you get the "reveal" for your guests on the smoker. Bark will be nice and crisp. I'm gonna try this.
There is a difference between the two methods. Meat stops absorbing smoke in the 140-160 range. 6hrs oven/6hrs smoker will have less smoke flavor than the reverse. Even after 160 some smoke flavoring is added but it's from layering on the outside vs meat absorption. You can use either method to "control" the smoke flavor amount and you can also make adjustments by when you add smoke wood, sort of like hop additions. Most people I know the use the oven or foil do it in the later stages, there is a flavor difference between absorption vs layering, the absorption flavor is usually preferred.
When I use the oven I do it later in the cook, around the 160-165 mark-right around the plateau , but 80% of the time I do the full cook on the pit. The oven does seem to reduce the plateau time. This is when I do butt. Brisket I cook at higher heat and foil around the plateau, leaving it on the pit all the time.