When you buy a sample CD what you are buying is a licence to use the sounds in your musical projects. You don't own the sounds, you own a licence to use them. The CD producer or manufacturer owns the actual copyright. Many licences make specific mention of "music", you may need special clearance by the copyright holder if you wish to use the samples not in a strictly musical sense, for example including in a library or other sample collection. Thats why there are no samples of the CD's reviewed here to download, whilst I can use the samples to make music tracks I don't have the license to publish them online.
The terms of the licence will usually say that you can use the samples in a musical context without further notice or royalty payment. Some licences make reference to the fact that you must acknowledge the source of the samples on documentation of any commercial release.
One grey area I believe exists is where a CD producer has sourced a sample from another copyrighted release. If they have clearance then fine, the user should be OK as he can plead the terms of the licence on the sample CD. However if they don't, you have that number 1 hit, who will the copyright holder be after, the CD producer who sold 500 sample CD's or the artist who sold a million, one for the lawyers.
Lastly, if your planning to release something commericially that contains something from a sample CD check the CD packaging carefully. Most times there will be a licence agreement, read it and make sure you understand the terms. There are some sample CD's that don't allow you to use them in a commericial release without prior permission !. If in doubt ask, and ask first.
Akai S1000 reads Akai S1000 & Akai S3000
Akai S3000 reads Akai S1000, Akai S3000, Roland & Emu.
Akai S5000/6000 reads Akai S1000, Akai S3000, Roland, .wav & Emu
Roland S760/SP700 reads Roland, Akai S1000 (though slow to convert)
Roland S750/770 reads Roland
Emu E111X/ESI32 reads Akai S1000 & Emu
EMU E64/EIV reads Akai S1000, Emu & Roland
Kurzweil K2000/K2500 reads Akai S1000, Akai S3000, Emu, Roland, Ensoniq & .wav.
Ensoniq ASR10 reads Akai S1000 and Roland.
Remember that even if your sampler recognises and can read non-native formats not all of the program data may be readable in addition to the base sounds.
This really is a quesiton of ease of finding the sample versus ease of using the sample
Audio - Pro's -
CD-Rom - Pro's -
The ideal solution is to get both formats, though cost usually precludes this. Once you've selected a sample though you'll wish you had the CD-Rom version.