I’ve been using 24-bit 44.1kHz for any audio material since the first MacOSX computer running audio applications (a 2 x 867MHz PowerMac). I never had any performance problems, and it’s really good I didn’t go down the road of creating and using 16-bit samples. The additional 8 bits give far more dynamics range.
The upper end, whether 44.1kHz or 48kHz, or even higher, is a big topic of discussion, especially in the mastering side. Some think it’s good to have more higher end for especially software synths so that any filtering will happen far beyond the hearing range. Others think it’s overkill. I could live with 44.1KHz, it maps nicely down to CD and MP3/AAC release versions, so there’s one less sampling I need to need or worry about.
Anyway, with most of the material as 24-bit or MIDI instruments, the output needs to at some point be rendered down to 16-bit for CD, MP3/AAC and so on products. This is where you really need to do dithering of the 24-bit material down to 16-bit in the the final rendering. Logic Pro has excellent dithering algorithms you could select. Of some reason Ableton Live still does not have any. I’m using Izotope Ozone for the final dithering from Ableton Live, myself.
So what is dithering, really? The Dithering with Ozone Guide over at the Izotope web site has excellent explanations what is happening. But shortly, if you take down 24-bit to 16-bit, the software needs to approximate values, so it doe something like average, and it makes the transition points very digital and harsh — believe it or not, adding noise up there will make the digital curves smoother, so the ear hears the final result more pleasing.
While you are at that web page, download and read the Mastering with Ozone Guide as well — even if it’s using Ozone as the example, it has tons of excellent advise about mastering, I try to re-read this document every three months or so to keep my mind fresh about mastering issues.
OK, enough mastering posts — marketing next!