Just a data point. I was unsuccessful in getting an UberX pickup from LAX. 4 times drivers accepted and then canceled. Apparently UberBlack or UberPlus are the only way to go, as they have some sort of permission to pick up at the airport. (this may change in the near future according to media).
I ended up taking the FlyAway bus to get downtown.
By the way, ever single Uber ride I took during my 4 days in LA was on surge, ranging from 1.4 to 2.5.