If body size/style is equal (i.e. LB SRW vs. LB DRW)
- Dually is a bit more trouble to park, not really a big deal, but a little more careful approach
- Putting extended reach valve stems on dually tires is a PITA, particularly if one rotates tires often
- Dually setup has noticeably less traction in snow and ice all other things being equal
If you need or might need the carrying/pulling capacity, get the dually: the above issues aren't terribly significant. If you're sure you won't need the capacity, go with the SRW.
Simple. :)