So here is a new submission with the original version plus 5 more variants that have some more features on the edges. Make sure you click every preview image to see the full version, otherwise you see scaled images again scaled by imgur 
Surprisingly they look pretty clean even down to 32x32, just for 16x16 I'd say the first variant should be used. But mixing isn't a problem, e.g. for the ProtoShareQt client you can use an .ico file that contains different variants for 32x32 and 16x16.

Hope you like it.

http://imgur.com/a/P4Txs