Code:
A lot of people are really afraid of delta printer calibration but the truth is it's pretty easy. Get the three settings above correct and then match the plane of your endstops to the plane of the bed, which are never relatively parrallel. The good news is getting the endstop plane to match the bed plane should be pretty easy too. Endstop corrections can be done in the firmware or manually by loosing them and moving them.
Keep watching the MarlinFirmware/MarlinDev branch at GitHub. Or who knows??? Maybe it shows up in the 'Firmware Enhancements to Marlin' folder here. There is a killier Delta Auto Bed Leveling routine well into development that is going to show up in Marlin soon. You will be better off calibrating the bed as good as you can physically. But if you don't even bother, it still will print OK.