I think most stories have been about backhand - I picked up lefty forehand much easier. I injured my shoulder, just slightly, in spring of 2009 and had to take a couple of weeks off but didn't want to - so I spent that time fiddling with lefty throwing and realized that I could get massive use on the course with the extra reach a lefty forehand gave me in the woods. Compared to a step-over stance ("patent pending") a lefty forehand could get me about two extra feet of reach. Plus right away I was getting a bit shy of 365' (the longest hole I got with it) on a high flex.
After I went back to throwing competitively a few weeks later, starting with 60' throws, I slowly increased the reliable range over time until in the right (very bad) situations I could use it out to the low to mid 200s. I think the highlight in competition was that fall using it on a snaking shot through the woods to park and save a 3 on a 260' approach that fall (that was big helping save cash in a tournament that otherwise fell apart lol).
I took to it well because although I'm a natural right-handed person I hurt my right arm and had it in a cast at the age my Dad was starting to toss balls to me and get me to toss it back, like somewhere around age 2? So I was doing all that lefty, and I wound up playing baseball as a kid lefty as a result (I hit righty). Though I didn't learn to, like, throw footballs or shoot basketballs til I was older, so all other types of throwing I do righty. Lots of lil stuff you learn at that age that I do lefty... hold a pencil, toothbrush, food utensils, etc. So thats all lefty stuff for me.
Throwing a baseball though has shifted over to righty since I started high school, I guess eventually tossing everything else that way overtook the baseball years.