1. Misfires
2. The short (semi) reliable working distance
3. Expensive batteries
4. Short battery life
Well Jeremy Kuster will show you how, with $20 and a little bit of work, you can overcome these problems and more.
In his tutorial Jeremy will add an antenna to the transmitter to increase both firing reliability and shooting distance, add a AA battery pack to the receivers to increase your shooting time and dramatically decrease your battery costs, and finally he walks you through adding lanyard to the receivers for safety and ease of use.
The tutorial is well written and photographically documented, making it easy to understand and follow.
The video below is from Roy Niswanger of Motley Pixel, in part 1 he tests the Cactus system (documenting its short comings) and in videos 2 through 4 he uses Jeremy's tutorial and walks us through modifying his Cactus triggering system and was kind enough to let us watch over his shoulder while he did it.