Sorry for the slow reply. Some answers:
Our officially supported Cortex-M platform for Java ME Embedded 3.3 is the KEIL MCBSTM32F200, which is based on the STM32F207 chip. There is a very similar STMF32407 chip, which is used on KEIL MCBSTM32F400 and we've verified Java ME Embedded 3.3 works there as well. It is likely that Java ME Embedded runs on other platforms using the STM32F207 or 407 chips, but it is impossible for us to verify all these platforms. If you get a chance to try one of those we would love to hear about your experiences.
For Java ME Embedded on ARM11/Linux: RasPi Mod B is our officially supported platform. Unfortunately, the Linux support for some of the peripherals needed by Java ME Embedded (such as GPIO and I2C) is inconsistent - this is a function of the state of the Linux device drivers, not of Java ME Embedded. We are looking into providing wider support for ARM/Linux platforms in the future, which isn't difficult, but we just haven't gotten around to it.
Generally, when deciding on specific hardware for a particular use case it very much depends on the details. If it is a customized system based on the STM32F207 or 407 chips then the need for porting/customization of Java ME Embedded should be minimal. If it is a customized system based on ARM/Linux, please contact us as we are already looking into widening support for ARM/Linux. Finally, if you are targeting a system that is very different from the above, then you can work with Oracle or Oracle partners for an optimized port of Java ME Embedded to your platform.
Finally, we are planning to provide support for additional platforms in the near future - stay tuned for announcements.
Hope this helps. Let me know if you have more questions.
Product Manager, Oracle
Thanks for your reply! It is clear now.