This shouldn't matter at all. If you place a unit on the map and another x distance away, it doesn't matter if that distance is measured in meters or yards it's the same distance away, the same point that it's at.
As for speed, again it shouldn't matter at all. Any given speed is equal to whatever mph/kph/kts. The computer should be able to convert all of that in it's sleep, why should we have to as a mission designer? Set to whatever units you feel comfortable and leave the details to the computer.
If you want 200 kts KIAS, set that and leave the whatever mph/kph and atmosphereic conversions to the birds. :) There's simply no justifiable reason not to have multiple values in the ME other than "We just didn't get around to it". It's really just a value display issue. There are no technical reasons for it that can't be solved.