Can the DAC on your Android actually benefit from the FLACs? Might make sense to re-encode the library into a format better suited to the playback hardware and leave the FLACs at home where the audio hardware benefits from it.
Well, if you've only got a portion then the only difference between having 10% and 99% is how frequently you have to copy new music on/how long you can go without having to copy new music, at least in my case, where I delete albums off the phone as I play them, and copying music between linux server and android phone via samba/wifi is fast and simple. Streaming - ugh... i use public transport including the tube, I fly (sometimes), I end up in areas without perfect coverage, and I listen to flac so you can't stream that well, and it would take a lot of data, and the choice is limited, and I'd be renting music not owning it forever. Streaming doesn't solve a single problem for me (my daughter loves it, though).
music is an extremely personal thing though. I guess I shouldn't be surprised that people have very different usage patterns.