Vintage Stem Failures - Question

Think I read Sheldon Brown write about vintage French stems being a bit dodgy, and was looking up Velobase and noticed the AVA 'Death Stem'! It states that it failed partly due to bad casting, but also because the conical expander uses two slots - one on either side. I noticed there's no circular end to the slots as well

Now the point I was reading this stuff... I bought a GB stem for £2 the other day and it just arrived. It has this two slotted design for the conical expander.
Is this stem expander design known for a lot of failures?
Or was the bad casting as much part of the 'Death Stem' reputation of the AVA!?
Should I be worried to use it, or is it totally common?

Was going to polish it up, but can't be bothered if it's a danger!

No one got any info on this?

I have to admit that I've never even seen a GB stem like that before. It could be a 1980-'s one to go with their 'Fabrique en Engleterre' handlebars.

What I initiallly wanted was one of the Hiduminium ones. But bought this to take a look at. Guess I'll polish it and try it out. Hopefully it won't fail!