I read Eduardo Mello uses Assembly over C. If you're low on mem as is always the case with retro homebrew probably assembly is the way to go so as to avoid the overhead. But man, assembly is brutal at least compared with C.
Totally... The Pac-Man Collection is unbelievably good, can't wait for the Donkey Kong Arcade. Gamester81 just did a review on Opcode Pac-Man Collection BTW...
http://gamester81.com/pac-man-collection-for-the-colecovision-review/
. You can find that