yellow I don't think anyone would argue that IGCSEs are hugely more difficult.
Ultimately these are all the most basic of exams!
However, I simply cannot thin that the most selective schools in the UK would specifically choose the easier option.
To be honest, they're not going to rise or fall on their GCSE results. They get and would get enormous amounts of A*s whatever the kids sat.
It's all about sixth form and where DC go thereafter.
Also, I have no axe to grind here.I have twins, one sitting GCSE and one IGCSE. I see the evidence daily.
In addition, I think the most selective universities did and still do pay close attention to GCSEs, both the subjects taken, grades etc.
And whilst the world and his wife were dong modular exams with re-sits a-go-go, there was definitely a perception that an A* won at a linear/terminal exam (be that IGCSE or GCSE) was a better indication of ability.
Obviously, Mr Gove has now scrapped modular GCSEs so things are equalling.
Finally, what I can see from the two different set ups, is that IGCSEs leave a lot of space in the timetable to simply teach.
There are no CAs and ISAs and orals that can be prepped in advance. All things which eat in to the precious time a teacher has with their students.
The process is not one of stop/start, but far more organic.