After a bit of use, I think I like the VAMO. I have noticed that the battery just stops firing on low resistance cartos much sooner than on standard resistance. I know low resistance mods on VV/VW mods seems silly, but I have a ton of them, and it's been hard to wean myself off them. The 1.5 cartos start to peter off when there is about 3.6 volts left on the battery - but I throw on a standard resistance carto, and get a lot more time out of it. I don't know if that is normal or not, but it is what it is.
They did ship me the new unit with the upgraded springs, and the rattle issue is gone. I am quite happy with it. Of course, the issue is still ongoing - since only one of the units was broken, they told me to ship the broken one back, and they would replace it, and send a new spring along with the replacement for the unit that worked. When the package arrived - they shipped me an extra VAMO by mistake. I contacted them to let them know (it just didn't feel right just to keep it), and they offered me some store credit if I would send it back. That was nice and everything (not that I'd be using it anytime soon), but they told me they couldn't give me a shipping label, but they would instead give me more store credit to "reimburse" me for the shipping cost.
Maybe I'm weird, but that just irritated the hell out of me. I'm happy to send the thing back, but hell - I don't want to have to PAY for it...