If your track record with Naztech was a little better, I'd probably just tell you to buy another because there aren't a lot of great 12v options.
Tekkeon MP3450 (ideally the "i" version) - I'm quite happy with my Tekkeons, but they have a terrible track record with the DR-680. I also think they're they're a bit overpriced with a smaller capacity than their competitors, but the feature set is generally nice.
Bixnet MP100 - This thing is a beast; truly an awesome battery. The only thing I don't like about it is that it is fairly big. Perfect for a festival, but perhaps a bit too big to lug to the average show on a weeknight. I think it would power the DR-680 for two days straight! j/k
Bixnet PM66 - I have never used this battery, but I believe it's the same manufacturer, Novucell, as the Battery Geeks batteries. Those were awesome, but have been discontinued. I don't like the pigtail and the other models had direct output jacks, but I appreciate the simpleness of these batteries. They're basically just like DVD batteries, but higher voltage and better build quality. At $129, I probably wouldn't buy the PM66, but I think there are a few others here that have run them and like them.
Anker Astro Pro2 - Similar price and size to the Naztech. I think there are few people here that use and like these. I don't own one and can't say, but have generally liked the Anker brand and products that I have purchased in the past, including macbook pro replacement batteries.