I still have several portable MD players I bought new in the early 2000s. At the time, even on high spec PCs, the software was slow as hell to convert music to their proprietary format. MP3 wasn't speedy, but it wasn't nearly as slow as converting to ATRAC. I remember it taking on the order of hours to copy a CD to MD. The quality was better than MP3 so it was worth it in the end, but an annoyance nonetheless, and probably didn't help adoption in the US (we want it now dammit!).

> The MP3 format spelled the beginning of the end for the MiniDisc.

That should be "the iPod spelled the end". MP3 and MD coexisted for quite a few years before the iPod's arrival.