Battery life is surely better, I am saving around 60-80uA from this upgrade (in idle). In active detection mode the saving over the chinese PIR is around 200-250uA.
Basically the rapid firing of many repeated triggers is somewhat unnecessary. The problem is the pulses are completely irregular. So if theres a constant pattern of motion for 5 seconds, the pulses are just all over the place, there could be 30 pulses in those 5 seconds, maybe more. So while pulses only happen with motion (which can be useful sometimes) the lack of having a pattern would make it difficult to make any determination of what's going on other than just knowing there's motion. In my case all i want to know is when motion is detected. Then i want a single packet to notify the gateway, and i don't care if there's motion for another 30 seconds. When I come home, take my shoes and coat off, and spend that half minute to a minute, i only need to know about 1 motion event, not 30. But again, yes continuous motion can be useful and the fact that you have control over debouncing is a plus. In their DS or an app note they actually show the "typical ciruit" which includes hardware debouncing.
In terms of adjustability, don't get me wrong, I think the Panasonic PIRs are great overall and less is sometimes more (lack of pots) but I haven't used these long enough to just discard the need for any adjustment. All we need it for it to just work so if it's smarter and doesn't need us to find the sweet spot, and it just works in most scenarios, then its a win.
BTW this would be a great blog entry if you shared some code