Please pardon this thread drift.
Roger,
"Also, having the DWR on the outside would be very good".
Don't the manufacturers of PU coated nylon tents put the coating on the inside of the tent?
Wouldn't you want to do the same thing with the DWR finish on the M90 or Intrepid?
"Some PU-coated nylon fabrics have a Durable Water-Repellent coating (DWR) on the fabric. In principle this should stop the fabric from absorbing any water: the water should bead up and roll off just as some pretty catalogues illustrate. But what those catalogues don't tell you is that the DWR does not last very long out in the open (a year or two), and the DIY versions for home use seem to last even less time".
The above was copied and pasted from bushwalking.org.
Party On,
Newton