Hi there Sparks59
All went well with the process in the end. The shipping company who brought the bike over got the bike through customs and provided me with the customs documents. I did have to pay an import duty, but it seemed to be calculated on the basis of what I told them it should be (I gave them AED1000 for a bike which is worth considerably sufficient for the import duty to rightly be far more than that!) . Once I'd got these docs I just went straight to the RTA here in Dubai, together with the insurance I had had to buy here and the RTA processed it without too much effort - I had to buy a Dubai plate, but it wasn't much (I forget the actual price now) and they even fitted it to the bike there and then!
The Dubai Red Tape Guide says that you need to get export plates to both officially drive around in the UAE before you get your UAE plates (I rode around for a couple of weeks on my UK plates with no problems) and to get the UAE plates at the RTA (I was never asked for them by anyone!) - the Red Tape Guide is useful, but after my experience I wouldn't stress too much about what it says.
So all in all it's definately worth it if you can somehow cover the cost of shipping it over to the UAE in the first place!
Now I just to repair my bike after trashing it the other week riding around Hatta Pools (with these guys - www.UAEride.com • Index page)!
Peter