Not a problem mate. There may be a couple of quid difference in a can but i think it's worth it still. Any paint supplier that can provide matt nato will be able to provide satin as well. I would say that satin is more forgiving when you apply it.
If you click my profile you should be able to see a picture of a soft top 90 (matt nato green applied with a brush) hooked up to a big flatbed trailer. I cleaned the 90 the day before the picture was taken and it hadn't been anywhere dirty, but you will see what I mean about matt paint 'holding' the dirt.