As of late last night, I'm proud to say that my Balancing Rock Canyon is now controlled entirely by reed switches! I have a magnet in the third car trip the first switch, activating the relay which turns on the rocks as the train starts to enters the section. Then once the entire train enters the Caverns, another reed switch flicks the relay, turning the rocks off.
Even though I did get an Atlas Snap Relay, I ended up making my own relay from an old Life-Like turnout. The snap relay didn't really operate to my satisfaction, since it required a lot of power (more than most of my transformers put out), buzzed quite a bit, couldn't switch completely sometimes, and heated up a bit.
Using the same idea with the solenoid controlled switch, I took the old automated turnout I had (since I wasn't going to use snap track anytime soon again) and turned it into a relay. I soldered one wire to one rail and the other to one of the switch points, so when the two touch, a circuit is made. To my surprise, it works! It doesn't just work, it works GREAT! The neat thing about it is that it doesn't take much power (so I can run it off the same transformer that's powering my rock motors) it's quiet, doesn't buzz, doesn't create heat, and is reliable every time. It was one of those situations that was kinda like "whatever floats your boat"; I'll be using my makeshift turnout relay for as long as I want, as long as it works every time.