I switched from SABnzbd to Newsbin to use with Couchpotato;
However, I have not been able to download anything since the switch. Here is an example of the couchpotato log:
INFO [.core.downloaders.sabnzbd] Sending "xxxNZBxxxx" to SABnzbd.
ERROR[.core.downloaders.sabnzbd] Failed sending release, use API key, NOT the NZB key: Traceback (most recent call last):
ConnectionError: ('Connection aborted.', BadStatusLine('\xdc\x87\xb5\x8bO\x15\xc6\xaa\xac\xbfK\x9d<4\xe9\x05\x98l\xa5~\xcf\x84\x87\xdb>"\xc6\xb3\x0c\x18\xeb^\xe6\xfa\x8e]\x86L\xa5\x16\x8eg\xda\xfb-\xf6\x19\xb1\xdb\xcd\x8a\x13r\xafn{X\xb3\xba\xce\x8b\xd6\x9c\x02',))
I followed the instructions to set it up here: http://help.newsbin.com/index.php/V660-NewFeatures
Note that I did not use an API key, and there is no username/password in Couchpotato