Just a little note on asthetics froma woman's perspective. It needs to meet code - of course. But ALL conduit is unapealing to the eye, flex, rigid the lot. If you want pleasing it needs to be buried (out of sight)in the concrete. Very few people outside our industry look at electrical infrastructure and say WOW that looks like a neat job. Same goes for the utility closet in the hotel - who cares if the utility closet is full of snaking conduit - just so long as the door closes and is painted in the same decor as other doors on the floor. In the parking garage the same could be said for those monstrous sprinkler standing pipe connections and pressure regulators - they look horrible - and then they go and paint them RED!!!
Agreed on the structural weakening issue - being one myself. But the point was folk who care about the asthetics of the buildings that they live in, and have the money, bury or hide all of that kind of stuff.
I pulled, or should I say, Helped to pull, 500/4 al MC. However it was concealed, and conduit would have been impossible. Not a lot of fun to pull, I must say.