The G28 and G29 use different probe methods. You can safely ignore the differences between the two functions. It does appear your bed has a significant tilt to it. The less that the Auto Bed Leveling has to correct, the better the job it will do. If you can't get the latest Release Candidate (Actually... You are better off with the Bug Fix version of it...) to work for you over at https://github.com/MarlinFirmware/Marlin/tree/RCBugFix you might want to consider this fork: https://github.com/beckdac/Marlin This fork has most of the good stuff folded into it and it is very very stable. It is not suitable for Delta's however.