I also solder them on pre-tinned with my resistance solderer. Like Gary, I am having trouble justifying them for using on turnouts, but on long mainline trackage, they show up pretty well, especially in well-lit photos. I'll wait until I have my trackage properly painted, weathered and ballasted before posting photos.
Since flanges don't come straight down (at a 90 deg. angle) I've found that placing them on the inside of the rails doesn't cause any interference...but mine like Skibbe's are clamped and soldered simultaneously. I can see if you ACC them on, you could possibly not get them properly positioned against the rail web, which would cause interference.
As an aside, when you get your frets of N-scale detail turnout and rail parts from Proto87 Stores, you will be amazed at how small the frets are....then at how small the parts are!
Although I'm a detail geek, I'm still debating as to whether it's worth it to apply most of Andy's detail parts.
