As a native American English speaker who has lived in a country using the metric system for the last year (and a few other times previously), I can tell you that the Metric system is WAY, WAY better in all respects. Whether 0 Celsius is the freezing point of water, or not, who cares? There are 100 divisions for all measurements.
500m = .5km both are used here, and both are super easy to understand. Yeah, it takes me a bit to 'translate' in my head to the distance I grew up with, but it's not that long before you just start thinking in metric. The imperial system is much more difficult than it needs to be; really, 1 mile = 5280 feet?!?! Stupid!!!!
As for temp, yeah, there are a few less gradations in temps that we normally talk about, and hearing that it's 25 degrees outside brings a thick jacket to mind before shorts, but it only takes a little bit to get used to the fact that 25 degrees is really comfortable. Whether it's 77 degrees F or 77.5, whatever, the gradations are very sufficient for understanding how warm something is, once you get used to it.
I wish the US would just make the switch already, and start benefiting from the incredibly convenient metric system.
Oh, and MC can use it too, even if we have English set as the language