Well, since camagic necro'd this one and there's one interesting point here that hasn't been replied yet..
I am still surprised when some endgamers say they think titles are a waste of time and energy. That person with 500 titles gets 5 hp for each title so has free 2500 hp, add the calculations for buffs and it is even more. This is free hp on top of stats gear etc.. Seems well worth it to me.
If title hunting is what you find enjoyable, by all means go for it.
If you are so very endgame that all the remaining growth options are time-inefficient, then by all means do titles for HP.
If it's convenient to do just a little something more for a title, sweet go for it.
But otherwise, no.
You're going to get some of those titles naturally from just playing the game. Let's pretend you get 100. I have no idea if that's a good estimate, but I'm betting it's a low estimate. So the title hunter with 500 titles has 2000 HP more than someone who hasn't tried at all.
Now let's pretend that 2000 HP can be doubled from buffs. Trying to be generous on the estimate again, I actually think it's less. Then you have 4000 HP more. Grats, that's slightly more than the HP ghost stat on 1 top item. Endgame players of every class can hit 200k HP. Healers/tanks 300k. Tip top 500k HP. So your hunting for 400 titles netted you maybe 1% to 2%.
Now think of the enormous time it would take to find those 400 titles - and not the easy titles that everyone gets just playing the game. Could you really not find gear upgrades, a new zodiac pet, a new food/potion, a pile of cards you don't have yet, level your secondary class higher, level your pet, or some combination of that? (Note: cards are almost the same situation as titles, just tradeable.) Chances are, most any of that is more time-efficient than hunting the difficult titles.
The folks I know that are pretty high on title rankings often have large gaps in their gear. They enjoy the title hunting, so it's good for them. But in terms of pure power gaming the gear etc is the way to go.