I've done a bit more research into this, looking at license agreements from companies who really know how to write a license that covers every base, e.g.
istockphoto's audio content license.
Seems to me their license specifically covers everything:
1) You can make musical compositions for yourself or for third party clients, no problem
2) You cannot send copies of the licensed sounds themselves to those clients, nor can they receive the music in a format where they can directly access or extract the isolated licensed sounds. So basically, the default intention is that you provide the client with a ready-mixed master of the entire music (so the $15 beat guys are happy)
3) If the client wants stems where the licensed sounds will be isolated and therefore easily extractable, the client has to accept they should purchase their own license for the sounds from the original sound publisher, as the beat maker himself does not have the right to transfer his license, nor sub-licence it.
I feel that's a pretty decent license agreement. This ensures the only person who is allowed to utilise the original sounds for music creation is the actual license holder, while the client can still have a music made for them under that license. I would assume clients wanting music for soundtracks, computer games, film & TV etc, are not likely to want stems, they just want a single, mastered WAV file to drop in to their project.
However if the client does want that extra control to perform additional mixing or compositional changes themselves, then he simply also has to buy a license for the sounds (or have the producer buy it on their behalf as part of his fees). I believe in practice, the type of client wanting full buyout and stems isn't going to think twice about this minor cost, the only people who would baulk at this idea are the guys who live in the $15 beat world.
Ultimately any producer who expects to be able to have the power to just freely give away third party licensed sounds to all his clients is being completely unrealistic. The whole point of sound licensing is that only the license holder gets to a) possess the sounds themselves, and b) make the music with the sounds.
Anyway, I think I got that out of my system now
