I came up with a different system for the MUX64 (required by the memory system) that doesn't use the CCPBRL system :

It uses full on/off switching instead of constant biasing so it might be less sensitive to individual drift in characteristics. This means less binning. However, there could be one side that is more ON than the other and heat more.

There is a big trick as well : the capacitor replaces freewheeling diodes to "precharge" the opposite branch when the relay switches to the other side. The question of the capacitance is important because I doubt that 100nF will be enough and the 100µF capacitors are polarised, they would be destroyed...

I have to evaluate the pros & cons of this method versus the CCPBRL one. For example, CCPBRL has only static/medium current and homogeneous/distributed heat but requires another higher-voltage power supply rail and requires very precise power supply regulation.