No misting under my Spinn tarp, none. I love that stuff! But, at $18/yard it certainly isn't the cheapest option out there.
A theory was discussed here many moons ago by Michele (I think) that said if you pitch the sil tarp a bit looser than you normally would it would allow enough slack in the sil to absorb some of the impact and prevent most misting issues. I have not tried this in an extremely heavy downpour, but have tried it in moderate storms with good success. Seems to work, but somebody needs to report after a really hard rainstorm.