Is there a way to find out if the enhanced G29 has been incorporated into the latest release?
As it turns out... Almost all of the Enhanced Pieces of firmware here have been folded into the Development Release of Marlin at GitHub. The most notable exception is the Topographical Map only displays the bed with the Origin at the Left Front. You have to mentally (in your mind) rotate it to another position if you have your origin in a non-standard place. The saving of the G29 Correction matrix to EEPROM is currently not implemented over there yet either. But I expect that to show up in 3 or 4 months.

Currently, the bug fix phases is ending, and the code is being locked down. It is very possible that a first Release Candidate will be published at the end of this weekend. My suggestion would be to wait a few days, and cross your Configuration.h settings over to that Release Candidate #1. If you have any problems or discover any bugs, everybody will be in a mode to understand and fix things. So the timing works out quite well for you! And as soon as the support issues quiet down, the only thing you will have to do is take your current Release Candidate #1 Configuration.h settings and compile the Release Candidate #2 (if things go badly) against them. Or maybe Release Candidate #1 gets promoted to be the 'Stable Release' in which case you don't have to do anything. You will have the latest and greatest code.