Using the ST-E3-RT is wonderful. Before going Canon RT I had a transmitter mounted to my Sekonic L-358 and fired my flashes via a receiver on the camera. That all changed with the Canon transmitter.
I now use Auto Reset Cordless Flash mode on my L-358. Carrying around the Transmitter was a pain when I needed two hands. I cut a spare mini stand (the one that comes with a flash) down to size and attached a spare Black Rapid connector. It now hangs from my belt or belt loop and I make all the adjustments at location. When done I just pop the transmitter on the camera.
This is my second mod. It was hard to lock the foot on the generic mini stand and I did not want to wreck the rubber seal. I cut up the foot that came with the flash and ordered a new one from Canon.