On my to-do list, I've added an auto-tracking hi-gain receiver antenna for use with 5.8GHz video systems.
The idea here is that because you have telemetry feeding back the exact location of the model, it becomes a trivial task to create an auto-tracking system that will ensure a hi-gain (highly directional) video receiver antenna is always directly pointed at the model. This will, in most cases, completely mitigate the effects of the higher path-loss (ie: normally shorter range) of the 5.8GHz video equipment and even allow lower-powered video transmitters to be used so as to reduce the risk of desensitizing a 2.4GHz RC receiver and extend battery life.
Anyone interested?