I’m using Seeeduino Xiao for fast prototyping. The powerful MCU and compact form-factor make it ideal to be embedded directly into the finalised product.
Design E meets this use case.
Powerful MCUs make large projects possible, hence the need for debugging. I use debugging to identify and fix bugs, and also to improve speed in critical functions.
I really like the Segger Edu mini and Ozone GUI debugger tools, managed from Xcode using the embedXcode plug-in. Please refer to my review of the Seeduino Xiao board and the connection currently required before the Premier Expansion Board.
RTC is interesting for low-power operations. The core MCU is in deep sleep and the RTC wakes it up to perform tasks.
The Feather form-factor is an emerging and popular format, with a rich set of FeatherWings, or shields in Adafruit parlance.
Boards with a rich set of sensors is a growing category. See for example Adafruit Clue, Arduino Nano 33 BLE Sense, BBC micro:bit, Microsoft Azure IoT DevKit to name a few.
Design A could fit into this category.
If you need a beta-tester, feel free to contact me!