Seem to recall that you built an excellent silnylon tent with fabric from Extrem Textil in Germany, and live and trek in Scotland, where wind is more of an issue due to the open terrain.
So am kind of puzzled why you are concerned about the Moment. At any rate, I've camped considerably in a silnylon tent, but it is stretched over a dome frame, and has a dome-shaped net liner. In that setup, the silnylon canopy has never gotten me or my gear the slightest bit damp. I have the original Moment, but have not used it due to the sagging that can become an issue when silnylon is not fully supported.
I say "can become" because there are silnylons coming from the Far East now that have more water resistant coatings, like the ones sold by Thru-Hiker, and also sag less when the temp drops. I've comparison tested them stretched in hoops on my back deck in the fall, so am pretty sure this is the case.
I say "fully supported" because silnylon is probably the most elastic of tent fabrics, and that, coupled with the sagging, doesn't bode well for tents that have larger spans of unsupported material.
But this thread is the first I've heard that silnylon acquires more condensation than PU. The thinking on BPL seems to be that this has to do with 'emissivity.' I think by this is meant radiant heat loss, and it appears that surfaces with less of that acquire less condensation. A lot of tests have been done with fabrics with reflective surfaces, but don't know if comparison tests have been done with silicone and PU coats. I also would not want a tent that was coated inside or out with a reflective surface. I did try out a very light PU nylon canopy this summer, but since there was very little sagging and a net inner, there might have been significant condensation that I just didn't notice.
But you've struck a chord with me, because I've already decided to use either shaded Cuben or very light PU coated nylon for the canopy on my next tent project. The floor will be the more water resistant silnylon, though. For a floor, I think the elasticity and resistance to sticky gunk are a real plus.
For photos of the above tents, look at the recent thread that started out about Sierra Designs new quilts and soon turned to discussion about their new tents.
Will be interested to see what others say about this subject.