I downloaded some 24/96 albums from HDTracks. You can never speak in absolutes on these things because there are so many variables but they clearly sound better to me. There's a certain something there (an anolog sounding somthing) that is an improvement over regular redbook. I wold have everything in 24/96 if I could. Nicely fluid, detailed, organic, whole from top to bottom.
Absolutely; theres no question about it. Also try http://bluecoastrecords.com/ which has a limited selection of exceptionally well-recorded acoustic material, which is recorded live on location and produced/recorded with great care. The Keith Greeninger stuff is fantastic (you can listen to samples prior to buying the download). The files are in 24/96 WAV, but you can convert them to Flac if you want to via "Foobar" (which is a free download).