I read the linked article the first time it was posted. My question was probably unclear, so let me try again: what happens in a crash that would prevent the belt release mechanism from working? It seems that unless the lock was damaged, it should still work.
Given the simple and robust construction of aircraft seat belt buckles it seems highly unlikely that it would jam and that you would need to cut your own belt. Probably not impossible, but highly unlikely.
The largest body of relevant experience is probably from auto wrecks. Awhile back ETS had a thread entitled
Cutting seat belts-How often?. The responses were interesting. You can read through it at your leisure, but there were a number of responses from ETS members who had decades of experience as EMS providers handling car wrecks. At least one had never had to cut a seat belt. Some had cut one or two in their career. Generally they only had to cut belts when the nature of the wreck blocked access to the buckle, or when undischarged air bags made it dangerous to reach over the victim to the buckle.
My take away is that needing to cut a belt in an aircraft crash is most likely when you are trying to free someone else, when wreckage makes it difficult to access to the buckle on their seatbelt. If wreckage makes it difficult to reach your own seat belt buckle at your waist, you'll probably have trouble getting free without help even if you could manage to cut the belt. Or to put it another way, if you can't even reach your own buckle, what makes you think you can reach your EMT Shears and cut your belt?
That's why my personal focus is on knowing how to unbuckle my own belt instantly without needing to think about it, and on quickly reaching and opening an exit. I'm not suggesting EMT shears (or a knife if TSA would allow it) wouldn't be good to have for other reasons, but it is very unlikely I will need it to escape my own seat belt.