I'm a hot n fast guy, wrap at 180 if making pulled pork, and still get a great bark. You could try hot n fast and compare it to your low n slow. I've tried spritzing and injecting. Didn't seem to do much for the flavor that I couldn't do better at the end by adding drippings and rub.
You can try some new flavors and ways to prepare that butt.
Here is a Carnitas recipe: http://www.smokingmeatforums.com/t/147751/smoked-pork-carnitas-with-photos
A couple more ideas.
Char Siu (I think this is the recipe I got from SFPrankster)
2-3 lbs of pork butt cut into chunks(1.5")
1/4 cup hoisin sauce
1/4 cup brandy
1/8 cup honey
1/8 cup soy sauce
1 Tbs dark sesame oil
1 Tbs grated fresh ginger
1 tsp grated fresh garlic
1 Tbs onion powder
1 tsp chili powder, such as african bird or thai dragon
1 tsp Chinese five-spice powder
1. Combine the marinade ingredients and whisk together in a bowl. Pour the marinade over the pork chunks in a sealable bag. Let sit in the refrigerator a minimum of 3 hours, but far the best if marinated overnight. Bring your smoker up to 300 and lay the pork onto the grill with a little space between each piece.
Smoked Pork Cuban Style
Okay, my apologies to anyone of Cuban culture. I was looking at Latin-style pork recipes and came up with the following recipe. The result was delicious. The tangy Mojo Sauce gave the meat a great flavor and fantastic au jus. It is different that typical pulled pork so if you're bored with standard fare, give this a try. It isn't dramatically different, just noticeably so.
4-6 lb pork shoulder
sprinkle oregano, cumin, black pepper
Mojo Sauce (pronounced MoHo)
2 cup Orange juice
1 cup lemon juice
1 cup lime juice
1/2 cup olive oil
1 tsp salt
1 large bay leaf
2 tsp dried oregano
2 tsp cumin powder
1/2 tsp black pepper
3 Tbs minced garlic (or 20 cloves fresh)
2-3 Tbs salt (add after reserving one cup of blended sauce)
Sauteed Finishing Vegetables
1 large onions sliced in thin rounds
1 red peppers, sliced
1 cup reserved garlic and lime sauce mixture
1. In a blender add the orange/lemon/lime juice, garlic, bay leaf, cumin powder, oregano, pepper, oil, and 1 teaspoon salt. Blend on high until liquified. Pour one cup of the mojo in a jar cover and reserve for later. Now add 2-3 Tbs of the kosher salt to the blender and blend again until the salt is blended into the Mojo Sauce.
2. Stab the uncooked pork shoulder deeply on all sides with a broad knife. Stab it deep.
3. Now take your pork roast, put it in a brining bag and pour the rest of the Mojo sauce all over the pork roast rubbing the mojo sauce deep into the pork meat in the slits or holes. The secret is to make sure you rub your pork meat roast with all this citrus/garlic sauce making sure it is well introduced into the meat. Remove all the air from the brining bag and zip tie it so the meat stays submerged in the sauce. Brine overnight or longer.
4. Next day fire up the smoker to 225°F to 250°F using a sweet wood for flavor like peach or apple.
5. Remove the brined roast from the refrigerator and pour the brining marinade into a sauce pan. Heat to a low boil and simmer for at least ten minutes for safety. Remove from the heat and let cool. You'll use this sauce for basting the roast and for wrapping.
6. Sprinkle a little more oregano, cumin, salt and black pepper over the entire roast again but just a little sprinkle.
7. Put the roast on the smoker and smoke until the first stall, usually around 150°F internal temp and roughly four hours. While smoking baste it with about a half cup of the Mojo Sauce every hour to 90 minutes. When it stalls wrap in a double layer of aluminum foil with a cup of the Mojo Sauce from the sauce pan.
8. I typically open my vents slightly and let the smoker temp climb to 300°F-325°F while the meat is wrapped. Smoke until an IT of 203°F-205°F. Remove from smoker leaving it in the aluminum foil and put it in a hot box or wrap in towels on the kitchen counter. Let rest for an hour or two. Total smoke/cook time is about an hour/lb roughly.
9. Just before serving pour cup of lightly salted reserved Mojo Sauce from the first blending into a frying pan with some oil. Add the onion and pepper and saute them in the mixture for about 5-10 minutes until tender.
10. Remove the roast from the foil, saving the liquids in the wrap. Pull the pork apart and add the mojo onions to the meat, mixing well. Or you can serve separately on tortillas.
11. The meat is juicy right after being pulled. Add a little of the wrap liquid to the pulled pork, but save the rest in a bowl and cool overnight in the refrigerator. The next day scrape off the fat and add the gelatin back into the pulled pork for additional tangy flavor.