This comes down to the specific equipment. 95% of 240V equipment is rated for 208V, but there's always something that isn't. You'd have to check the specs of each 240V appliance to verify.
Given Watts = V^2/R, 1-phase heating elements will be about 30% cooler and take longer to cook/heat water/etc, it's just the nature of the beast. Get them to switch to 3-phase appliances
