Should I switch to tank or stay as DPS?

[Penthea]

As a DPS,it takes,no joke,over an hour to assemble a full party

This isn't surprising considering Coils are not current content and they're not in any of the roulettes. However this may change in the future. Coils' counterpart from HW has been added to a roulette so I think it's only a matter of time until Coils will be added as well. If you want to do that content sooner rather than later, as someone else said try to use party finder or assemble your own group. Maybe this will yield better results.

If doing Coils is the only reason why you considered tanking but you still do enjoy playing dps, then I would say stay as dps. But the beauty of this game is you can pick up any class and switch as much as you like so really you can just do whatever