While Titan HM will definitely trip you up in a DF group, a PF group can work for a casual player. Two reasons for this:

1) A PF group isn't forced into having an unneeded second tank for the trial, and therefore gets the benefit of an added DPS.

2) You're forming up and able to communicate with everyone before jumping in. Also, the PF will let you know the tone set for that particular group before you join. I've seen a few "Newcomer's Welcome/Slow and Easy" groups for Titan HM.