I own the original Buzz Pro, like it a lot, no fears. Current limited design, high current diode "fuse", short circuit sensing, reverse battery sensing, 3 symmetric decent sized vent holes for minor venting and warning of something going bad, one piece metal top cap screwed into the main tube, bottom cap has delrin plasic threads that will pop out on a significant over-pressure. You can use either protected or IMR batteries with it -- notcigs is getting in Trustfire protected batteries, and the AW IMR 550 mAH and ICR protected 750 mAh also work fine with it, though I've been happy with the minimally protected Powerizers (since the mod has good protection built-in).
The Pro II/Lightning are indeed there because ECF asked for it, crafted a spec that essentially mandated such-and-such surface area of venting, symmetric along the sides. The BP delrin end cap would have met some of the earlier ECF postings on the topic, as it will pop before there's any chance the top cap would come off. If I bought a Lightning, I might add a small piece of plastic sheet with some vent holes punched in it to the interior, provides the vent path while minimizing opportunity for anything to get in the slots.
Some people do like the looks of the lightning bolts.
So, yes, essentially bureaucracy, notcigs complied rather than ignoring the spec. No tests have been performed to verify the validity of the ECF slot number/size specified that I know of, though notcigs did indeed check that the delrin end cap would come off on over-pressure (before ECF came up with the spec there had been notcigs discussion of the endcap being an inherent safety item). If it weren't for the set of safety features I list in the first paragraph, however, I'd be leery of solid tubes holding a lot of energy, and I personally include big single battery devices -- a large 18650 holds a lot of stored energy, more than in both batteries of a notcigs PV combined.
Buzz Pro and Infinity Pro have the same design features, so what I said applies equally to IPro.