It took me a while to get used to L2/R2 for aiming/shooting, but it's not bad IMO... you just have to hold the controller differently so that your index fingers rest on L2/R2 instead. I didn't know KZ had an option to switch so I haven't tried L1/R1, but I figured that I should get used to the triggers because some games don't have that option to use L1/R1 (ie BF4 AFAIK).
Yeah I am trying to get used to L/R2 shooting too. Have a sense more shooters will use them for shooting.