Due to the size of the house we installed two boilers running side by side (only one does hot water) so the channels/valves/boilers are pretty well synched and load balanced. Fighting over the wireless channel may be a different problem.
I thought ahead on that one (and also assuming all TV/music etc will be streamed soon) so we have a commercial (Unifi) wireless mesh network throughout the house that copes with the (very) solid internal stone walls.
That's worth looking into. The 'main' rooms each have three rads (and three large sash windows) so wiring to an overall room temp might work better than three rads fighting to be boss...
This is really good to know.
It's great that you have a strong WiFi solution (it took me ages to get mine right!) but be aware that this won't help you with a Drayton system nor, indeed, some of the alternatives - they don't use WiFi because the protocol demands too much activity and would flatten batteries in no time, so they use Zigbee instead. This also works in the 2.4GHz band but will generally run happily alongside a WiFi - there are some non-overlapping channel combos available. But the consequence is that you now have a Zigbee network that needs to be spread around the house as well as the WiFi. thus needing its own extenders. Not hard to do - the Drayton solution is to use their Smart Plugs, which double as Zigbee repeaters, which is fine - unless you're going to need two separate networks, in which case it might not be.