Also, I make no claims to being an expert on rechargeable batteries, but I have always understood that unprotected batteries are at increased risk of over charging/discharging.
My understanding has been that protected rechargeable batteries offer me an extra bit of protection, which I am happy to have.
I may be mistaken, but these are my simple understandings.
Not so much on charging. As that would be down to the charger to stop charing at the right voltage. I don't know of any protection circuits that would stop over charging. But you'd have to either being using the wrong charger or a faulty one.
Most protection circuits prevent over discharging. But they do so by acting like a trip switch. They will cut all power, turning the torch off. And the only way to reset would be to put them in a charger.
I did a runtime test recently with a Jetbeam light and supplied 18350 Jetbeam battery. Jetbeam claimed 55 min runtime, but the battery protection circuit cut power at 35mins. Turning the light off. Once I had reset the protection circuit the battery was reading 3.15v. Under load it would have been lower voltage.
Had it been a non protected battery the light would have stayed on a lot longer and you could have run the battery down to a static/resting voltage of 2.5-2.7v. Again voltage would be lower under load, but unless the torch has a boost driver, the reality is, the light would have just dimmed and the load of the battery would have significantly reduced.
But I can see why people like the idea of protected batteries. But it isn't 100% clean cut on the pros/cons. All IMO.