ASHP low temperature radiators ~ pipe sizes?

[Spoogster]

Evening all

Potentially joining the OVO Govt sustainable heat trial in a few weeks where the initial plan is for an 8.5kW Ecodan ASHP to be plumped into a new water cylinder and low temperature radiators.

Looking on the web there is a suggestion that the existing 10mm microbore in my house would need to be upsized to take a higher flow rate? I was of the understanding that low temperature 'fan assisted ' radiators held only 0.6 litres of water which is much lower than a conventional radiator let alone one that is over sized. 

Does anyone know if 10mm microbore is OK or is this Govt trial going to need massive disruption to replace all the pipes in the walls and floors etc?

Thanks in advance