Considering I specialize in non-DPS classes this hasn't really changed my play style any, but what I have noticed is that the "Player in Need" system is always a few steps behind the trend because it's either too slow, or doesn't properly account for player behavior when it does update.
What I've noticed is that if I sign up for a duty when I'm on CNJ and the "Player in Need" is Tank, it's almost instant that I get in. If it says "Healer" on the other hand, I often have to wait a bit.
From my observation it seems like the server just monitors the queues to see where the shortage is over a time period and then marks that class as the player in need for the next time period. Players find the change and jump in as it switches causing an immediate surplus of that class and a shortage of what the player in need was in the last time period. Basically, it's just flip-flopping between tank/healer pretty meaninglessly as pretty much everyone knows it's *both* that we have a shortage of (well, there are more warriors lately, but that's bound to cool off pretty quick once people get over the newness of the changes there).
I don't think it's a bad thing to try to encourage more balance, but the system as is happens to be a bit clumsy on a few points:
1. Only the "player in need" gets GC seals. That seems like almost too good of a deal for pulling people towards signing up as that class.
2. What the server says it needs is actually what it needed several minutes (an hour, maybe?) ago, not what it actually needs at the moment when people are signing up.
3. Only one class can be needed by the system at a time even if the truth is that the need is in more than one class.
I'm thinking if any one of these points were addressed, the system would probably behave a bit more like it was intended, and I have some ideas how:
For #1, reward everyone with GC seals, just let the "player in need" get more. That way people farming seals could play what they want to play and DPS don't always walk away empty-handed. Honestly, I've always wondered why FATEs gave seals but duty finder didn't.
For #2, make the measure real-time. If it says tanks are needed, it should mean right that moment there's teams that are only missing tanks. Being a software developer myself, though, I can understand how this would probably be the hardest to implement correctly compared to the other two options.
For #3, instead of rewarding one class 100% of the bonus, spread the bonus to whichever were in need before, but weighted in favor of the greatest need. For example, if the average team had to wait 10 minutes for a tank and 5 minutes for a healer, then tanks would get 2/3 of the "player in need" bonus while healers would get 1/3. It would pretty much work exactly as it does now, but wouldn't give the illusion that there's just *one* class always in need.
If you were to ask me, my vote would be for #1, but I'd be perfectly happy with any of them.