I was planning on redoing the cables and housing on my commuter and I stumbled upon this cheap cable housing on Amazon. I think it would be fine for my commuter but I know I'd have a lot extra. Do you think I'd notice a difference in shift quality if I eventually put the extra on my nice road bike?

Is that shift or brake cable housing? There's not enough information about the product. I am wondering if it is lined.

It's not worth the savings. You will curse the cables and yourself after the first inevitable glitch. Check out probikekit.com. They had complete brake or der sets for a decent price.

cabling isn't somewhere you skimp. You can ruin a nice groupset in a heartbeat with cheap cables and housing.