Julf
Facts are our friends
For music I really like and want to listen to repeatedly, I buy a download (Redbook or hi-res)
For music that is less important to me, or just to explore - streaming.
Streaming pays for itself, as I use it to decide that some albums aren't worth buying, when before streaming I might have taken a chance on them unheard.
Pretty much the same here, except I still buy the occasional CD (new or second hand) and rip them.