I started with the 510 and the battery life bothered me so much I had to order the eGo by the 4th day. I'm so glad I did. If I was going to buy another PV today, I'd probably want the eGo-n starter kit that comes with all the usual stuff plus adapters for other attys/cartos if you want and a few kinds of drip tips too. Plus the light is on the end.