A little word of cautions, many GRBL incarnation, don't use the latest version that is 1.1.
1.1. is different from 0.9 mostly on the controll mechanism between GRBL and the sender.
more problematic is that many cinese implementations, use the old 0.8 or even more old, some old versions have a limitation of 50 character in a gcode line, this limit could be easily reached using too much decimal places in the precision.
Many people have encountered problem due to this behaviour.
Regards
Carlo D.