I've been a TA for both semesters of orgo. It's much easier to digest the second time around, so yes, it was very helpful. The way the professor taught it, I caught a lot more details than I did when I originally took the class.
I would suggest trying to TA for a prof you have already had and make nice and hit them up for a LOR. I think the biggest benefit is getting to know a prof and getting a letter.