What made me ask the question was the Transgenic Sample 11
fight in Lost Island. Implicit in rDPS vs mDPS is cast/channelled attacks vs instant attacks. With sample 11, players are required to be on the run for a portion of the fight. In this case mDPS is a bit better as they can continue hitting with their best attacks. It sounds like this is not a major consideration though.
As for smuggler class: my wife is going gunslinger (sniper), not scoundrel (operative) since she wants to play rDPS and gunslinger has 2 ranged trees: sharshooter (marksmanship) and Saboteur (engineering). Giving it just a quick glance, dirty fighting (lethality) looks like a mDPS or short range DPS tree.
Thanks for everyone's feedback!