FWIW, I have an e-mail newsletter myself at http://rubyweekly.com/ and the way it is right now is the best I've got it to convert. Every time I removed more from the page, the better the conversion, and unsubscribe rates are low (about 8 in total in the last month).
Of course, flat out "lots of subscribers" isn't necessarily your goal and you don't need to optimize for that if it doesn't make sense for your plan.