I'll answer the OP directly then:

Who has a decent DD gear set up to switch to occasionally when not needed as a tank?
I do!

What gear are you using?
Ifrit's Blade
Canopus Shield
Cobalt Chain Coif (Red) (Materia: MP+28)
Cobalt Haubergeon (Red) (Materia: Crit Atk Power +24)
Cobalt Mitt Gauntlets (Materia: Atk Power +12)
Felt Trousers (Red) (Materia: STR/VIT+7)
Cobalt Sollerets (Red) (Materia: HP+40)
Penance

Dated Mythril Choker
STR/Acc rings situational

How are you faring against other classes?
Poorly as my linkshell is well-geared and they know how to play their classes.