I'm considering the new Lavatube. I'm also considering a Buzz Pro. Currently I own a 5v GLV2 and three Madvapes VV boxes.
I don't want to sway you, but I'm happy to share my experience.
First off, nothing will provide a better real-life vaping experience than your Madvapes VV boxes, in my opinion. I own seven of them, and sure, they're just cheap little plastic boxes, but they vape like champs. They handle whatever atty/carto I throw at them, and at any voltage I want, with effectively no voltage drop. And they hit like freight trains.
That said, I also own a BuzzPro and an iPro. Both are very well-thought-out and well-made.
I chose not to buy a V1 ProVari or a V1 Lavatube. While I had other concerns, the 2.5 amp limit was a deal-breaker for me when each unit first came out. Some people didn't care about that. I did and still do.
Over the past two weeks, I've purchased a
Lavatube V1.5 with a 3.2 amp limit from
crystalclearvaping (black tube only, $51.75 shipped). I also bought a
Vector Variable Volt (LT 3.0 with a 4.0 amp limit) from
vaporbeast (black full kit, $68.99 shipped). That's less in total than I paid for my BuzzPro blem. I also have a SmokTech VMAX coming from the co-op buy ($64.00 shipped).
Perhaps this will change, but right now I prefer both Lavatubes to any other PV I own. They vape just as well as my Madvapes VV Boxes, but they are so ergonomically convenient. A single button press gives me three invaluable pieces of data: the resistance of the atty/carto, the voltage setting, and the battery life remaining. This is brilliant, and both LTs operate precisely the same---same button press, same display. Only differences are the styles of top connector and bottom cap, plus different amp limits (although I doubt that I will ever need 4.0 amps). I like both styles, by the way.
Both LTs seem well-designed and well-built (especially for the price). In other words, they don't feel "cheap" to me. I can't speak to durability or longevity, of course. Time will tell on that. I'm glad I didn't buy an LT 1.0, and I'm equally happy that I did buy the 1.5 and 3.0.
YMMV, of course. Good luck in whatever you choose!