Tumblr and Twitter - Complimentary Services?

I have been using Twitter and Tumblr for the last 6 months and consider myself a moderate user of both services. I have Tumblr setup to read my Twitter feed, but my Twitters have now dropped off considerably. I still read my friend Twitters. Why no posts then? There are two main reasons. First, Twitter hasn’t been that interactive for me. Sure I have friends (not Twitter ‘friends’) who use the service, but they use it so lightly that it really doesn’t impact me enough to put myself out there. If it’s not interactive, why use Twitter? The other reason is that I can take advantage of Tumblr’s input and don’t require the text-message / fat-client of Twitter. Tumblr is more free form and I’m more pleased by the output, customization and free-form nature of the tool. It looks great on my cell phone and the flexibility allows more creativity. Twitter still has it’s place for that quick message and short input (if email isn’t available). But Tumblr now has my blog and my interest and Twitter is fading away.