I ran iTrials enough to get my main up to +4 on two branches of each slot. I did it mostly to see if I could before getting completely fed up with it. I did not grind the iTrials because I thought they were well-designed celebrations of fun. I liked feeling like a powerful superhero, which the iTrials most definitely did not foster; they made me feel like puzzle fodder. Taking my Incarnated main back out into the conventional L1-50 world did though...and if there was any real benefit to be found in the Incarnate powers, for me that was it.
In fact, I felt that the iTrials were the least-CoH-like content ever delivered. I didn't like the fact that defeating the bosses meant learning how to navigate the gimmicks that utilized mechanics not found anywhere else in the game. All the "superhero expertise" gained in levels 1-50 were made irrelevent by virtue of autohit attacks, attacks for which there were no defenses, unique mechanics (like Sequestration in BAF) that no other mission prepares you for and which no other missions make use of. The continuity of gameplay expertise felt violently severed, so much so that the iTrials felt like an entirely different game. I think it is called WoW...
Everything I loved about CoH made me loathe WoW, which I gave a try for about 6 months after taking a break from CoH (around the time the AE was introduced). Imagine my horror when I returned to the game only to find this intriguing Incarnate system was little more than short-form WoW dungeon raiding. I'm sure it appealed to the WoW expats who felt themselves on more familiar ground when they got to it, but it felt like nothing more than a tragically missed opportunity (to add "end game content" that truly felt congruent with the spirit of CoH as a whole, which is to say congruent with the L1-50 game). And the fact that trial leagues always felt compelled to max out the roster, spending more time waiting for qualified members than the trial itself took, made the process a whole new kind of tedious.
If CoT decides to improve upon CoH, I dearly hope they reconsider the end-game phase and conscientiously avoid copying other MMOs. None of them "got it" when it came to understanding what made CoH special. It would seem that the architects of the Incarnate system lost sight of it themselves.