Could you be more specific by what do you mean with centralized?
Are you talking about the number of simultaneous IPsec tunnels possible to establish from a single device?
In that case only limited tests were carried out on RUT955. It was confirmed that the router can sustain up to 40 IPsec tunnels,by having all of the remote devices to ping RUT955 over IPsec at the same time.
The rest depends on your needs and bandwidth requirements and bandwidth available on the central device.