I think the recipe is calling for slice pork which can be done at an IT of 170. For pulled pork, you will want to the IT to be at least 195, thus the extra time. If you are going for pulled pork, then you could estimate about 1.5 hrs/lb to get to an IT of 195-200, but you will want to also add in time for resting of about 2 hours. The rest time is done in heavy duty foil, double wrapped and in a cooler if you have one handy.
The temperature setting is also important...the recipe on the site has a set temp of 200 (if I recall), but you will want to go higher than that for a boston butt - I usually set to 230F.
Last weekend I did a 10# BB that took about 12 hours to reach an IT of 203, but again, you want to allow factor in the rest time to your estimate. It is always better to start too early and have time on the back end, then to start too late and miss the desired time for eating!