I have a curve CU with 16 RCBOs in it and have room for two more RCBOs.

Ever since it was installed 6 years ago, we have never had a nuisance trip.

With RCDs often protecting several circuits, it does not take many leaky devices to add up and the total leakage current go over 30mA which is the trip threshold for RCDs.

With RCBOs you have a trip threshold of 30mA per circuit rather than of half the house circuits in the case of a split load CU.

We did have a real trip due to a faulty iron but it only took out the lounge and the master bedroom. (Wifey was ironing in front of the lounge wood burner).

Worth every penny even though RCBOs do not cost much more than MCBs and the saving in not buying the RCD helps too. :-).

It will not surprise me if the next wiring regs mandate an all RCBO CU instead of current split load CUs