I’m not convinced but I have seen a frameset I like which is discounted. I much prefer a standard threaded BB – as that is what I am used to, seems more straightforward and no horror stories of creaking.
Hope, Praxis and Wheels Manufacturing (to name but 3) all do proper convertor BB’s (not the Heath Robinson adapters to sleeve the BB down) and are fairly readily available. You just need an LBS with a Hope account (quite a lot), or an Upgrade account (again, a lot), or a Madison account (every LBS really).
I’ve been using the “cheap” SRAM PF30 adapters to run standard BB cups.
Having an interference fit between a plastic part and metal frame isn’t great IMO – mine slightly un-located (by maybe a mm on one side) after an off, which caused a bit of an issue over time.
I read-up about it online and people were securing them using a particular type of loctite – which I then did, and it’s been fine since. However, if the Hope/Praxxis versions had been available then – I would have just used one of those. Threading both cups together makes much more sense IMO, and arguably makes more sense than having BB threads in the fame.