It all sounds so hard and annoying! Do you think you could say you've made many sales through it, or useful contacts, that make the extra effort worth it?
I think I've made useful contacts. And I have interacted with a few fans of my work (which is great highlight) but overall I hate doing it. The problem is the cost of time. A lot of time is required to maintain a daily presence, and half the stuff on Twitter I find to be mind-numbingly superfluous. o.o