The thing is, if it's pure or mostly sand, it will freeze solid like concrete for significant parts of the winter where you are. This is really hard on chickens' feet, both in terms of bruises/cuts and (especially) in terms of encouraging frostbit feet if they spenda lot of time out there.
I would suggest that if you are going to use sand you should figure on most-likely adding some straw or some such thing atop it for wintertime. This will also intercept much of the wintertime poo. Then whenever you have a thaw and/or it's thawed enough to be getting gross, rake the used straw all out of the run (to compost for garden) and replace with fresh stuff. When the ground thaws for real for springtime, just remove the straw.
Doing this will mean that you no longer have a pure sand run -- you will NEVER get all the straw bits out of there, not even close -- but that is not necessarily a problem unless you had visions of doing daily poo pickup with a fine-tined rake or fork. You will still have a mostly-sand run that behaves pretty well in terms of avoiding mud, and of course you can always top it up with more pure sand whenever you feel necessary.
JMHO, good luck, have fun,
Pat
