I think its clear they must refund if people ask for a refund. 

What people need to realize is that their only protection other than shipping in a reasonable timeframe is bankruptcy.  If they go there, then you are *NEVER* going to get a refund.. bankruptcy *protection* protects them against you (a lowly creditor behind all the bondholders and banks.)

I would make sure people think long and hard about what happens when the difficulty increases faster than the shipping can keep orderers happy.  I think you could make a prediction here either way, but the very real possibility that they declare bankruptcy is certainly a possible outcome.