Sheerly in terms of technical quality, my experience has been that the best 
platinum prints I have made have been double coated. I'm a little surprised 
at Terry's comments because this was the conclusion we reached together a 
few years ago - togethers with the other points he mentions.
However it is possible to get very good prints with single coating. An even 
easier way to get excellent prints is to buy the machine coated paper - with 
which it is simple and routine to get results that equal the best single 
coated prints, although of course without the wide range of paper surfaces 
available for hand coating. 
Peter Marshall
Family Album/Gay Pride  -  http://www.dragonfire.net/~gallery/index.html
Also on Fixing Shadows: ----------- http://fermi.clas.virginia.edu/~ds8s 
Future Press and elsewhere...  E-Mail:  petermarshall@cix.compulink.co.uk