I would suggest the following:
1. Lower the height of the stand as much as possible. This allows a better view into the vessels, makes filling them easier, makes emptying spend grain easier and finally, there's not good reason to make the stand tall except maybe to impress the neighbors or something. A shorter stand will have a lower center of gravity and it will be inherently safer, but that's really more of an incidental benefit.
2. Use different burners. The Banjo's are too hot. This would be better: http://www.agrisupply.com/burner-cas...82/cn/5400000/
with this variable pressure regulator: http://www.agrisupply.com/product.asp?pn=64640
3. The cooler will melt if you run burners on either side of it as shown and they will melt in milliseconds if you use the Banjo burners. The top rail will get very hot when the burners are in operation.
4. Use larger hoses. I would suggest using at least 5/8" ID extra thick walled tubing throughout. Make this change now and you won't need to replace the smaller hose and all of the connectors later on.
5. Use gate valves in lieu of ball valves wherever precise flow control is needed. Ball valve are fine for full on or full off, but not so hot for flow control.
6. Use Digital thermocouple thermometers and forget the bi-metal type dial thermometers. Trust me on this one.
7. Consider not building a monolithic stand at all. Instead, consider building it in a modular form using two or maybe three separate modules. This would allow you to move the cooler MT module away from the burner modules so it would not be affected by the heat. You could build the modules in a way that they could easily be connected together when and if desired. A modular stand is also easier to move and store. Some of the stands I have seen require a forklift to move and must weigh about the same as a Tundra. Design it as a good minimalist architect would.
8. Your basic setup appears to be intended for straight forward batch sparging only. If you ever plan to do step mashes, you may want to consider automating the burners and making it a RIMS or HERMS type rig.