Each DLC increases the cap by 5, meaning that at the end of Lonesome Road you could be a frankly godlike level 50 (!). If you have Dead Money, I'm assuming you're level 35. Honest Hearts + Dead Money = level 40. http://bethblog.com/index.php/2011/05/03/details-on-honest-hearts-old-world-blues-and-lonesome-road/ reveals that Old World Blues is next in line, in June - realistically taking the trait will cap you at level 40, when you start the DLC. So, post Honest Hearts, when you're lingering somewhere about level 30, will you take the capping trait?
I play hardcoe Mode with my main character, but if all this new trait does is freeze my level I'll be very hard pressed to take it. I RP my Courier as the Lone Wanderer with plot convenient amnesia, so being an unstoppable unkillable messiah syncs well. Mind you, I'm an unstoppable unkillable messiah at level 35, and in Broken Steel at level 30 it was quite easy to be omni-competent at every weapon, fighting style and wasteland discipline.