It will likely work - the wattage essentially means the maximum current draw the battery can provide, so you might find that the bike can't accelerate as fast with the 1000W battery. You might also reduce the battery's lifespan by running it near the limit, though the bike won't be drawing 1200W...
I currently have a radiator central heating system, controlled by a Nest with OpenTherm (combi boiler, no zones/valves). I'm now getting an extension built which will be one big room from the new structure and the existing kitchen and dining room. I'd like to install underfloor heating in this...