If you own a Sapphire Pro, you know the dilemma. The factory firmware (typically a stock Marlin build) works. It will move the spindle, read the endstops, and run a basic GRBL-like G-code. But "works" isn't "best." The best firmware transforms the Sapphire Pro from a machine you fight with into a reliable production partner.
It usually includes a much better UI and better support for BLTouch/3DTouch leveling sensors. Essential Calibration After Flashing two trees sapphire pro firmware best
Marlin Firmware Service – Sapphire Pro config If you own a Sapphire Pro, you know the dilemma