I have two idea's i think would work.
1. Have titans cost 8 cap ship points. Increase cap ship points to 24. This means you still have your 16 cap ships and a titan or 24 caps ships. Simple to do the game can handle it as we have palyed a 4 v 4 lan game with i think it was 48 cap ships per player and the game ran fine so the engine can handle it.
2. Limit them to travel only without your own gravity wells - im not too fond of this but i think it would work and stop titan spamming because the way the game is now you can just to build a titan as fast as you can (22/23 mins?) then just send it at the enemy and keep doing that letting it die over and over and over until its level is higher
Keep titans as are - let them keep their XP bo to build them required the following research
Level 8 Defense - Titan Hull
Level 8 Weapons - Titan Weapon Project
Level 8 Civilian - Titan Foundry (titan foundry should not be under tactical because the game mode win the game without building any tatical structures means no titans)
I dont think that the titans should not retain their XP regardless of what if any changes are made between now and the release.
I think the idea of 24 cap chips vs 16 caps and 1 titan would change up the game play nicely, especially if your titan loses a level - which of these two would you all prefer - 24 level 10 caps or/vs 16 level 10 caps with a level 10 titan