The main thing I've read is that they need to stay moist but not damp in order to preserve the beneficial bacteria in it. Personally, I think that even if it dried out completely the bacteria will go dormant but still live in it. When they make Bokashi Bran they saturate it in the beneficial bacteria and then dry it out before sale. If the compost has the consistency of mud it may cake if left to dry out for long. Maybe stirring it up periodically will aid in preventing this.

Have you pulled out worm cocoons? If not I think you will find that by the time you need it again you'll have a colony of worms in that compost. Probably not a problem since they should be able to keep things aerated and chew up any remaining organic matter. You'd just be doing another worm harvest in the spring. Extra work for some, but I think for the average "hobbyist" on this forum it's kinda fun harvesting since there is such a long wait in between starting up a bin and getting finished compost.

Come to think of it the best way to store over winter might be to put the compost in a large rubbermaid tub (holes in the lid only) with a handful or so worms and leave them be until you need them. If you're not adding new material then you shouldn't have any excess moisture to deal with. If they die off they decompose quickly and should just become more compost. I am going to have one of the trays in my WF about done this winter so I think I may try this.

Hope this helps, it gave me a new idea to try out.