Actually, I've never played FFXI. My point is, if it's a hybrid, it can't be a "carry", as you've so put it, otherwise why bring pure DD classes that bring none of the so-called Utility you speak of? RDM would be something similar to Paladin in WoW. The slightest changes/nerfs/buffs to the class itself can manifest in horrendous overpowered/underpowered performance in a hybrid class. In order for RDM to be viable, yes they will have their rapiers and their magic, but they're not going to, and honestly shouldn't be able to, out DD a DRG/MNK/BLM, and they shouldn't be able to outheal a WHM.

So, what does that leave? The utility. And, like I've said previously, if their utility in the forms of buffs/debuffs with damage/healing don't make it worth bringing a RDM over another DRG/MNK/BLM/WHM, then they'll never be a viable class. Don't get me wrong, I want to see a RDM in this game. The aesthetic of the class is just way too awesome. The difficulty comes in how they are implemented. Honestly? My idea of a RDM would be take the Fencer class from Tactics Advance, and the RDM abilities would be Saboteur/Synergist abilities from FFXIII with, of course, Double Cast as it's something of a staple of the job now.