I too had heard of issues with early models - so beware if you are looking for a second-hand one. I have seen the Beehaus on eBay now and again. Now they have been around for a few years, there will be some knowledge of how the plastic ages - whether it gets brittle or if the colour fades for example.
We had an old Dartington (the same concept but made of wood) at our association apiary. It was used to put cups of tea on at the time and I don't believe it was in regular use - so I have not used one unfortunately. I do tend to move hives around the apiary from time to time in a slow dance of less than 3 feet a day - say - in order to combine one colony with another, this may be a problem with a big double hive; you couldn't easily move one of the two colonies to another location to unite with another stock. If you get one, let us know what you think of it!
May your bees read the same books as you do.