I have it 'working,' but it slows down the device a lot when it's downloading.

It burns about 50% CPU when downloading, so it's not really feasible to use it for much unless you have a power source handy.

I think getting greasemonkey or something similar to nzbstatus and perhaps a homescreen widget and running sabnzbd on a server would be a better solution in the end.

Edited to add: That CPU usage is based on a download speed between 200 and 300KB/s.