Yea Im not sure about the so called inexpensive engines as an advantage, the conversions seem to do the job just fine. If you like to tinker its even better. Plenty of engines available next to free. CDI ignitions and prop hubs available at hobbyking fairly cheap.
Im new to the game so maybe theres something I dont know? Glow fuel and lipos are so pricey, so why not try one conversion at least.