Still on my first pair of SPD-compatible shoes, a pair of Sidi Dominator 4s that I paid a hundred quid for (new) about ten years ago.
I don't consider myself to have wide feet, but found that the 'Mega' (wider) fitting was right for me.
Sidis are almost indestructible, and so comfortable. I'll replace them with Dominator 5s when they finally kick the bucket - you get what you pay for with shoes, imo.
M540s are my pedal of choice whether on MTB or road bike.
I wouldn't put flat pedals on anything other than a pub/cruiser bike now (which is what my Cannondale became before I stripped it).