As it stands with the current system, your character gains more points to put into their build each time they TR, but after the second TR, they stop becoming more powerful (and are only given the passive past life feat for the class they picked first/leveled the most in).
Here's what I think should be done to make TR'ing more interesting:
1) Enable post-36 point-build TR's to continue gaining ability points with which to make their characters more powerful. Up to a 46 point build.
or
2) Grant an occasional/additional free feat that is related to the class that a TR has an active past life for (up to three). For instance, I TR'ed from a paladin once, so I would get a free feat that is related to the class that I currently am (however, if I TR into a wizard from a paladin or fighter, I would not get any free feats unless I TR from the wizard into another arcane).
and/or
3) "Liven up" the passive and active past life feats.
To counter these suggestions, the TR would then be locked into doing the quests on hard, elite, or even a new difficulty level that's between elite and epic (there would be a greater chance of named loot/tomes dropping, but it would not contain any named-item upgrade components as an epic quest would).
EXP would not scale beyond 36 point build requirements, but the monsters would scale to the player(s) power in addition to receiving a generic buff related to the increased difficulty level of the quest. This would make the game much more challenging (and, perhaps, on par with epic-level difficulty), and beating these challenges would require a thorough understanding of your character, game mechanics, as well as teamwork.
Thoughts anyone?