I agree Bill. It can be hard for people to understand what living in a frozen land entails. Later this week the sap will run, and then it will be work keeping up.
Sean is right observing that if the sap goes cloudy it has gone bad, though I am sure you are aware of that. I have stored sap in slightly warmer weather for a number of days with no degradation.
My 2 cents on the sugar content of the ice - I suspect the conventional wisdom that light ice carries an uneconomical trace of sugar is correct. But, nothing speaks like facts, take some ice samples, measure the specific gravity. I believe you are correct that heavily frozen sap has the sugar entrained and shouldn't be discarded.
Much like the hard cider technique, i have read of home distillers concentrating mash by freezing, then thawing to the free crystal stage, claimed to work effectively, so cold could be an advantage to some degree. Testing will provide proof.