To elaborate on my experience as a new player, I felt the DPS comments aimed at me were valid.

In the second dungeon I ran, we had a DPS player who clearly wanted a speed run. He complained that we were slow, and pulled extra packs of monsters. He indicated that I had both the time and mana to cast more than just Thunder and Aero, and while he wasn't polite about it, he was technically correct, so I've tried to step up my damage contribution since then.

On the Ifrit Trial, I was told that when the Nail appeared I needed to stop healing and only DPS, otherwise we would wipe. I failed to do this the first couple times (resulting in wipes), because I was too busy trying to keep everybody healed up from all the AOE damage. What that taught me was how to prioritize my heals (the Thaumaturge, for example, needed healing ASAP, because he couldn't take more than one fire breath attack without dying), and things went smoother once I was able to get a full DPS rotation on the Nail right away.

Otherwise, things have gone well. I like healing in this game, and I haven't had any complaints about my healing performance. I've only had a couple rough patches with wipes. Of course, there were aforementioned Ifrit wipes. And I also caused a couple wipes when the DPS speed runner pulled too many monsters, and I wasn't fast enough with my heals to keep up (though I eventually managed to succeed at that too). Anyway, I'm willing to take the blame for and learn from those mistakes, and I feel like I'm getting better at healing as a result.