Hell, what happens to Arduino?
At the company I work for, we've replaced all the Atmega chips in our products with the STM32F0 series chips for lower-end requirements and with STM32F4 series for higher end stuff, because they have more grunt and generally have more peripherals, and are similar prices.
I have personally developed Bluetooth stack using the GCC tools for the MSP430 using the CC246x Bluetooth modules and it was a blast.
So you have a lot of options with free tool chains. I personally use only free toolchains on linux. It is the best development setup and you have a lot of options for debugging and tool development.
Though if Dialog is power management IC company, maybe Atmel's microcontrollers or Atmel based boards will have better power management features and/or be more power efficient?