As you all know, downloading a huge .zip file takes a long time, as does uploading it in the first place. And if you're using Dropbox or another service with a capacity limit, smaller would certainly be better.
FLAC files are lossless, and are generally at least 50% smaller, though tracks with a lot of silence compress much more, I just compressed a 58mb vocal track to 2mb.
There are some good free apps for batch converting the tracks to WAV or whatever you prefer for use in your DAW, if FLAC isn't supported.
If you have a favorite conversion program, please post a link below, and indicate if it's a mac or windows application, too!
Hopefully, if everyone is onboard with this, we can make the file exchange process faster and not too complicated.