It's mostly that I just want to have good pulling strength, but I find it very hard to make progress with regular chin-ups. So, I was looking to the L-pull-up as an alternative, interesting, and fun way to continue working on that. Just a slight weight variance completely changes the difficulty. Just an increase of 2-3lbs can easily be the difference between a 3 rep set and a 2 rep struggle for me, and then doing further sets after a struggling one is simply impossible. That's like eating a large meal pre-workout, rather than a small one, or forgetting to remove your squat shoes before moving on to chin-ups, or drinking too much water. It's also weird that I set my 3RM record of 50lbs at a bodyweight of about 178, and now that I'm about 200, that's difficult for me, but my ability to do a OAC negative has improved dramatically (gone from absolutely no control whatsoever to a 1.5-2s negative).
I am also working on ICPO's 3x a week, but want to keep some bent-arm pulling too (eg. a pull-up variation).