Ogg Vorbis is a fully open, non-proprietary, patent-and-royalty-free, general-purpose compressed audio format for mid to high quality audio and music at fixed and variable bitrates. This places Vorbis in the same competitive class as audio representations such as MP3, and similar to, but higher performance than MP3 and many other audio codec formats .
Vorbis for samples
Vorbis is a destructive compression format just like MP3 so why should you use the Vorbis version of a sample or a sample library? Disc space and to get some workload off your hard drives. One situation this might be important is when working on big projects, as a lot of streaming from disc will clog up the system. Another is to cut off initial loading times for big sample libraries in for example sforzando. As it takes a bit of CPU usage to decode a Vorbis file it might not reduce your system load in any practical sense. The biggest pro of using Vorbis is to save disc space.
Hey, what about quality, man?
Yes it’s true a Vorbis file will not be exactly a 1:1 representation of a recording but it can be goddamn close. To hear the difference between a high quality Vorbis and a Wave file is for most people, if not all people, impossible. When working with audio I am very cautious about using as high quality formats and gear, but at the playback stage it might not be that important. When you add to the equation that a sample often only contains one sound playing at one time and the nature of how Vorbis work a Wave sample might not give any practical advance over a Vorbis encoded one.
So what should I use, the Wave version or the Vorbis version?
Well I can’t really give you a straight answer, you, your ears, the amount of disc space you got and your level of anxiety over sound quality has to make that decission.