My two loops at one end don't have much room, so I used the #4 switches for the crossover. They work fine, but obviously stuff like the Challenger or Big Boy sure look funny going between the two tracks! 
I actually cut these down on the thru path a bit to fit them into the straight section, the curves start right after the switches. I added a length of track between them as I wanted more space between the tracks, which is also why I had to cut down the long end. The length of track between them also does smooth the transition and resultant S-curve a bit.
I have to trim the roadbed yet, I'll get to it one of these days.
