Very easy to program (they use BASIC), very inexpensive (no fancy programmers needed) and lots of routines built in ideal for R/C modellers. For instance- routines for controlling servos, receiving pulses from R/C receivers, easy communication with serial devices which enable extended functionality.
A Picaxe or two can equip you with hundreds of channels on your R/C set, for less than a fiver. Or it could be a custom failsafe, flash lights in sequence or move servos in a preconfigured routine at the throw of a switch. That is just scratching the surface. The only limit is your imagination and programming skill.
Fundamentally, PPM R/C is 1960's technology, that's why you're limited to 8-channels- extended channels are achieved by fiddling with the standard, which is why you have to use proprietary (read flipping
expensive) receivers for those sets which have more channels or use multiplexing like the Robbe modules.
An infrared system for your build could be built around a pair of Picaxe 20X2 processors, with a handful of extra components. Cost would be about $14-15. You would need to add to this the cost for motor control components and any power transistors required for switching the LED's. Also you would require some sort of enclosure and off course the switches to operate the various functions.