I am considering an upgrade of my old consumer unit, which has rewirable fuses(2 lighting rings, 2 power rings,an immersion heater radial and a cooker radial).A split CU would be OK, with RCD+MCB protection on the power rings & cooker unit and MCBs for lighting and immersion heater. Would it be better to use RCBOs for all the circuits? More expensive I guess, but are there any other issues around RCBOs (reliability? ) that I should think about? The advantage would be that a fault would only shut down the circuit in which it took place.