Retird, I absolutely agree with you. Each user should make an informed decision. The OP (not the person, but the post they were referring to) just sounds like it was using a broad brush to condemn things.
I personally don't believe that a single battery VV is inherently magically safer. At the end of the day if something goes wrong it is about what venting mechanisms are available, the total energy available for release, and the chemistry (type of reaction). I don't know how many popular tubular VV other than the Pro start with the three symmetric vent holes, a plastic threaded end cap "blow plug", and then offer an option to purchase a model with extra venting (whether one likes or dislikes it, they at least offer the option). Notcigs did check the blowout pressure required to pop the delrin end cap, and the Pro top cap is a single metal piece -- no rational way for it to come off before the bottom goes. The tubes are over-sized relative to the batteries, which allows for some swelling, too.
For energy, a single large 18650 battery has more stored energy (watt-hours, voltage times mAh) than a pair of 16340 batteries combined, and far more than a single battery in a stacked pair.
For type of battery, you can buy protected ICR or safe chemistry IMR in 16340 size same as is available in the single-battery 18650 size. With a single battery VV, boosted regulator, IMR is the only valid choice that I've heard of due to the high current drain (drawing extra current to achieve > 3.7V). With the stacked battery VV, ICR becomes a valid choice due to lower current draw in the buck regulator implementation. I've run protected ICR in several of my notcigs products, as well as the "unprotected" powerizers (they actually do have limited protection, just not the full slate).
For the PV-level electronics safeties, again the Pro series have reverse battery, over current, over temperature. Nothing magic, but it's a good full set of things to have, I don't know what other VV tube mods have those features (possibly all, I've had no reason to check).
I'm very comfortable with what I use, would switch in a heartbeat if I had any worries. Any PV, whether single or stacked batteries, should be thought of in terms of where are its weak points if a battery has a bad day. Then, pick one in your comfort zone and use the manufacturer-recommended batteries (don't cheap out), and use a decent charger.
I pretty much had to survey the crop of what was available, perform my own due diligence to choose what I use. There are definitely other very good products available, including some excellent single battery VV, but I'm happy with my own choice.
