So I frequently want to delete them entirely. Good thing I can go to my iMac and do that. But I don't want to. - that is how you got non purchased music there in the first place right (imported on your iMac)? Whats wrong with managing music on your computer sometimes? Its a personal preference I guess.
I want to know if the song is on my iOS device without having to shut off iTunes, then search to see if it is still there. - if you are looking at iTunes Match ON you are not looking at anything on your device (at least permanently). If you have it set to iTunes Match OFF your a looking at music permanently stored on your device...delete away if you want.
Not to mention that turning iTunes Match back on takes several minutes while it downloads the XML data for the 25,000 songs. - I agree that would be annoying with that many songs, I have about the same amount. I dont really plan on switching back and forth that much unless I run into data issues. But thats just me
I used to be able to download a song from the cloud to my iPhone. Now I can't. I can download an artist, album, or a playlist but that's it. - I totally agree and I would bet that is one of the first things Apple fixes. I cant imagine it would be that hard for them to fix.
For you to play a song on your iOS device, it has to download to your phone. It may come in a stream, but it's going to end up on your phone. The same amount of data is coming whether it's a download (that starts playing immediately I might add) or a stream. - I know how data works...once you download to your device use a certain amount of data to get it there but after that you can play the song a million times and no data is transfered because it is being played straight off your device. The question is when you stream, how long is music kept in your cache memory before it gets replaced by other newer cached music and you have to use data to stream it into your cache again? If you play a song 100 times over a period of time, how many times did it leave your cache and you have to re-stream it? its a cache capacity question which becomes a data question.
Now you don't have that choice. So next time you want to play it, boom that's another download (assuming the temporary cache has cleared). So now you're using twice the data to play that song twice. Thanks IOS 6. - exactly, thats my question and concern right now.
I agree its not perfect and that is why they will likely get these things fixed. My whole point is I see people posting things saying not being able to delete individual songs is a bug in iOS 6 which is not true.