here's what you do.
buy the MVP.
wait a week.
sell the vamo.
sounds to me you already know what you need and your vamo isn't getting much use. i think a trial period is likely to really nail the decision down for you. assuming you're not vaping at 6 volts or over 11 watts on the vamo, the MVP is going to nail down all your current needs. also assuming this person considering buying the vamo is a smoker and not currently vaping, you have a chance to recoup a couple bucks while potentially saving a life and definitely saving a set of lungs... of a person who will then eventually pay that favor forward.
in the end, i think the trade off is going to be a win/win/win. but dispel your concerns before you go forward with offing "potential backups" so there's no "what ifs".
i have a vamo that gets no love and i've bought 4 MVP IIs myself. the mvp certainly gives a smoother vape and the battery life between charges is out of this world. only question is whether it's going to be enough power for you. by the sounds of it, it will suffice just fine. being you have a couple spinners and all.
honestly, i'd sell the spinners to fund another mvp... or just jump straight to a REO GRAND and enjoy dripping one handed like a boss all day.