So far I have had no misting with silnylon tents. That includes two from Tarptent and one from Six Moon Designs. You could get some spatter when there's condensation on the inside of the tent and heavy rain or hail hitting the outside, but I never did. After seam-sealing, I have tested all my tents with a hose, the nozzle set for high pressure, for about 30 minutes, to make sure there's no leakage. I haven't noticed any misting then, either.

Condensation is more of an issue, especially somewhere like the Wind Rivers where you're usually either above timberline or in a forest of dead trees. This isn't a problem specific to silnylon or single-wall tents, though. I've had so many issues with double-wall tents, in which severe condensation on the fly leaked into the inner tent, that I'd far rather have a single-wall tent where I can easily wipe off the condensation. Camping away from water sources and (especially) in the trees eliminates most condensation. If I were going to go back to a double-wall tent, I'd look closely at the Scarp--I especially like the idea of being able to pitch the fly first and put up the inner tent under its shelter. I understand that most European tents have this feature, but American tents don't. Regardless of the number of walls, though, there's still going to be condensation unless you can camp under a tree. Ventilation is most important, although even that doesn't help much when you're down in a deep valley on a windless night.

While painting spots or stripes of sealant diluted with mineral spirits on the tent floor and your pad does prevent your having to chase your sleeping pad around the tent during the night, I've found that it won't overcome the laws of gravity. If you're on a slope, you're going to slide, regardless of what your tent floor is made of! At least that has been my experience since childhood (and that's a long time!).

As for silnylon's stretching, the Henry Shires tents I've used are designed so you can easily tighten the guylines while still in your sleeping bag. By the way, I've found that my spinnaker Gossamer Gear Squall Classic stretches when wet, too! I'll have to run a backyard test to find out if it's the fabric (which isn't supposed to stretch) or the guylines that are stretching. Older style tents used to shrink when wet, so you have to adjust the guylines either way.