Seekburk
To be frank... they could be right. I had several issues with different PCs that led me to buying the MC and discounting the JB version.
Primarily, playback of protected files. MC did it with less trouble and more seamlessly. Also not all file types MP3, WAV, M4P, AND M4A (alac) files would not always play on the ASIO driver output. I would have to switch over to WAVE OUt or Direct sound output to play my old mp3 & wav files. that bugtged me some.
Another bug forced me to go get another codec for ALAC (m4a, m4p) files. Direct show. this works better than the use of the Quick time codec MC uses by default. it's a bit less edgy up top and a bit more natural overall. until you hear both, side by side, either will be fine though... the default or Direct Show codec.
Vista too using MC sounds far better than XP using the same MC media player on both OS. Don't know about Macs. I can't use them. Sure would like to though, just to see.