While we have --quite-build for emerge, rsync per default outputs every single file which gets transferred and deleted. Luckily, recent versions of rsync, which also went already stable, support new ways of progress output and since i use them already on other scripts i decided to modify my portage rsync settings a bit:
The output looks similar like that:
Neat, isn't it?
BTW, in order this works correctly - the remote rsync server need to run a recent version of rsync as well.