Just some thoughts:
The first Steripen was the Adventurer.
The first batch of Adventurers had a problem with off-state current drain – it was much higher than planned. This was fixed.
The company also flirted with rechargeables, but gave up on them after a while.
Steripen do warn against using cheap Chinese batteries – and rightly so. Many complaints come from using such cheap batteries.
The Steripen has been massively abused in the field and in the lab – without failures. They claim they even tested them using a spud gun!
I have not heard of any significant number of failures for the latest couple of generations – like the Opti and the Classic 3.
Add to this: If you really do use up the life of the lamp in a Steripen, I believe the company may replace it for you. And, while I know of a number of people who returned their Steripen Adventurers in the early days, I believe the company replaced every one of them free. (To the best of my limited knowledge.)
So – I am not sure I would rate the probability of Steripen failure very highly. But many have reported field failures of filters.
My 2c. Ymmv.
Cheers

