Just saw this answer. Thanks for the suggestion, Sam. I just want to be sure that it's a good investment and I'm not missing out on something that is so much better (and as easy to use).
It's definitely a good investment in terms of the KR808D-1 being an established product that many manufacturers support. It's not going anywhere anytime soon.
Yes, there are most definitely
batteries that last longer. If you get into mod territory, you can even get
batteries that last longer with equal or higher voltage.
The thing is, any change (aside from increased battery life in the same footprint) could be better or worse, depending on who's stating the opinion. If you're happy with what you have and are worried about whether dropping $50 or $60 bucks on some D1 batteries is a good idea, chances are you won't find something radically better in the same price range.
For some people, chasing the "perfect vape" is a hobby and they don't consider money spent toward this to be wasted. For most of us, finding something that satisfies us and fits our lifestyle is the only real goal. From what you said in the OP, it seems like you were lucky enough to find this in your first PV. As I said before, I don't see a reason to change unless you're dissatisfied with where you are.