When I first heard about the titans, I was very excited about the concept. After a few weeks of playing around with them, I am nowhere near as excited as I used to be. The problem is they are not a strong addition for multiplayer.
The reason is the game is becoming a giant game of "don't feed the titan". With Permanent xp and levels, there is every incentive for a player to risk his titan to kill a ton of frigates just to level it up. As a result players are afraid to bring in frigates until LATE LATE LATE LATE LATE game for fear of leveling the other players titan too high. Also, players are rushing the pirate base for experience and the guy who gets the level 3 titan from killing the pirate ships has a massive advantage.
Please, don't try to argue the "well if he goes to the pirate base, hes vulnerable elsewhere". I thought that too, but sins is slow paced enough where you can't deal a decisive blow while he is leveling his titan. Also, you may argue that suiciding your titan because of the cost and build time is foolish but if you take out enough ships to gain a level or 2, it was well worth it, because even if your opponent starts to push on you, you just bring your titan back out into play even more powerful than before and continue leveling it.
The only real and reasonable solution is to make it so xp and levels DO NOT carry over upon death.