Like you said, opinions vary on this issue. The one thing that people do agree on is that since this is an analog signal (as opposed to a digital signal like HDMI or optical), the cable can degrade that quality. That being said, I'd sleep soundly at night with those Monoprice cables in my system. I have a few and they're sturdy, high-quality cables that are just as nice as (and a fraction of the price of) some Monster RCA cables that I have.
The Monoprice cables and connectors are pretty stiff, so make sure that you have clearance behind your components. You can't mash them into right angles like you can with the flimsy RadioShack cables.