So I just unlocked Warrior...

[Gilthas]

... does this mean that I'll be parking my Marauder forever and only using it for soloing from now on? Or is it better to use Marauder before endgame dungeons?

[Gamemako]

Marauder is superior for DPS and a viable tank for Brayflox. If you're properly-equipped, you should be fine there. I wouldn't bother with MRD as a tank after level 35, though, because Inner Beast is pretty damn important.

[Eightbit]

Past 35-40 you will want to be warrior 100% of the time.

[Fuuljo]

If you have a lot of good cross class skills you'd be better off playing MRD for solo play. All of the Warrior skills are tied to Defiance and keeping up Defiance while playing solo will slow down your kill times.

That said you still get stat bonuses from simply being a Warrior so even if you don't have Defiance toggled on it's still worth staying as a Warrior, provided you're happy with having a limited pool of cross class skills.

As for tanking you don't really ever want to do it as a MRD once you hit 30. The benefits from Defiance and the rest of the Warrior skill set are pretty big. Brayflox's Longstop is where these things start to matter much more.

[Gamemako]

If you have a lot of good cross class skills you'd be better off playing MRD for solo play. All of the Warrior skills are tied to Defiance and keeping up Defiance while playing solo will slow down your kill times. That said you still get stat bonuses from simply being a Warrior so even if you don't have Defiance toggled on it's still worth staying as a Warrior, provided you're happy with having a limited pool of cross class skills.

Also a good point. You'll want to do most solo content (i.e. the easy stuff) as MRD due to higher damage output. When it comes to solo tanking FATE bosses, MRD is still fine if you have a chocobo healer.

[Altimis]

... does this mean that I'll be parking my Marauder forever and only using it for soloing from now on? Or is it better to use Marauder before endgame dungeons?

Just go Warrior until endgame, so you learn the mechanic too