You can do anything on a kettle that you would do on a smoker, but it will likely take more work and/or skill.
The Smokey Mountain is purpose built for smoking and does it with ease and aplomb. It holds a lot of charcoal, uses daisy wheels for precise temperature control and has space for a water bowl (or other heat diffuser/moderator) between the fire and two grates. the lid has a tall dome for large pieces of meat.
Gauge by how many you see on Craigslist. They don't sell as many as kettles, nevertheless, they almost never show up in the Chicago market which always has a good selection of kettles and gassers.