Arduino for STM32

EDIT - I've gone in a lot more depth now, and evaluated all the libraries that are even potentially included, even if not used. I found that the major difference between the two is the inclusion of stm32duino/STM32Duino FreeRTOS. As soon as I remove this dependency it starts working. I assume it is ...

Hi, for a long time I've had users of my libraries (tcMenu, IoAbstraction, SimpleCollections and TaskManagerIO) using STM32Duino. For some reason, I'd always associated the larger STM32 boards with mbed and never tried this core - I wish I tried this a long time ago!

So far I am really impressed ...