I've had a few clients go with .org or .net . My impression is that the general public is "aware" of .org -- there's enough of it in use -- although they may not immediately remember that your site uses it instead of .com . I think .net is more unusual and so perhaps confusing, for the general public.
I do wonder whether your registering a variant means that the desired .com domain will remain renewed/tied up, gambling that you -- or a competitor -- will want to acquire it.