We've developed a Dashboard using the Import option. I was naive to think that a move to DirectQuery would be easy. Subsequently I've realsied the difficulty in doing this as the queries to the data source are non-optimal and don't fit the mould for DirectQuery - they pull back too much data and I've got a nested join within my DAX code.
The easiest way around this would be for Microsoft to allow half houlry refereshes of the data with the Import option - why can't this be done?
Or I could have 6 versions of the Dashboard (i.e. 6*8=48) so I can have a least one upto date dashboard for each hhr during the day. ;-)