My experience
As a relatively new Hunter owner, I can't speak to Hunters. However, my previous boat I alternated winter storage between wet and dry every other year. Both alternatives have pros and cons.Wet: Pro- (1) MUCH less work in spring and fall since no mast unstep/step is done. If you hire your yard to do all of the prep and readjusting/runnning rigging work, maybe you don't care. (2) Less handling of the mast and all the rigging. I have had damage occur just do to the handling. (3) Much less expensive. Every turn of the hand by the yard translates directly into $$$.Dry: Pro- (1) Ease of inspection of all rigging and fittings, inch by inch. I feel this is necessary for peace of mind at least every 3-4 years. My preference is every other year. More often than not, I have found broken strands in stays that I would not have found otherwise. However, I believe that some of that damage was caused by the unstep/storage handling. (2) No worry of the safety of the boat- chafing of lines, rubbing on docks, sinking, etc. (3) Ease of bottom painting without the time limit pressure of a short haul. Other maintanence too, while it's out.Generally, the pros of one method are the cons of the other.Regarding leaving the spreaders attached- I never did on my old Morgan. Since my yard handles and stores the mast inside, I have no idea how they store it. I could ask, but I haven't. However, I do not expect any damage from any method that they use.Can't help on compression problems, other than to check for fiberglass cracking around the mast.Just my 2 cents worth, possibly only really worth a penny.