When person A says they like the Logitechs, and some other distant person B says they like the Cakewalks, what conclusion can you reach? None, I think. I don't know a reliable way to compare speakers, except by setting them up side-by-side and taking a listen.
One question: What is the purpose of these? Are you replacing the built-in speakers of some digital piano. If so it's pointless unless you actually buy speakers that are much better than what you have.
I think it was said right above, you are compareing low end studio monitors with a computer multi-media speaker. I'd go for the studio monitors. What you mostly care about with piano is the center of the keyboard. Monitors will handle this range well. The 2.1 system is designed for movies and games and foes the ends of the keyboard well.
You Do have to audition speakers. you can't just buy them based on specs. Bring your own CDs or iPod to the store and listen. Best to listen to solo piano music. Close you eyes and try to think if it ssounds like a piano or sounds like speakers.