Nope, the data connector is not the same between different brands of MP3 players. Third party support for the iPod data connector is huge, mostly because there are enough iPods with the iPod data connector to justify building third party peripherals such as chargers, clock radios and high-quality speakers with the iPod data connector dock.
Thank you very, very much. I sincerely appreciate your spending the time to give such a precise and complete answer. Cheers! :-)