The installation packages seem to be already well-compressed. My zip-program reduced the file size by only about 5Meg (out of 350Meg); it would take about a 100-fold reduction to get it down to a size that could be attached to a Forum post here. I don't know what the upper limit for attachment size is in my email but I suspect it's much less than 350Meg!
Starting last fall I was downloading and installing nightly builds once or twice a week. Around 15 Feb I got a version that corrupted files. I filed a bug report, the developers took action promptly; but I reverted back to the last version that worked for me. I was starting into a couple of significant projects, and watching the traffic on this Forum and the bug tracker, I decided I wasn't brave enough to risk a return to the nightly builds.
The version I'm running (R7628) crashes once or twice a week, but all I lose is my work since the last "Save". I have it installed on 3 different machines, all Win7/64, and one machine has the great majority of the crashes so it may not even be a problem with KiCAD per se.