For me the cost of forsaking C would be not to experience 100% programming freedom/power (which comes with 100% responsibility). And yes, C also gives you the freedom to do any nonsense :)
I was always fascinated how little resources are needed to run C programs, here an example (not by me): https://github.com/barteksalsa/avr-tiny12-disco/blob/master/... ATTiny12 mikrocontroller with: 1 KiB program flash rom, 32 bytes of "ram", 3 level hardware stack