Try it one week and see how many people unsubscribe. Our team is also very critical of email notifications so we try to think like normal users. As long as you make the email insightful or interesting, users wont mind.
A great v2.0 feature would be to use NLP and automatically tag and filter the user's tweets. It would be hard feature to pull off but it would take your product to the next level.
We email users every time there is a large update to the site with a fairly high open rate. However, not many of them return to give us another go.