The Particle Electron has recently caught my attention:
https://www.particle.io/cellular. Actual performance and usability are unknown, since the first units don't ship until later this month, but it has some attractive features:
- low-cost M2M-oriented international SMS/data plans ($3/mo. for 20k messages)
- STM32F205 MCU with 1MB flash, 128k RAM and 2 CAN buses
- free development IDE: https://www.particle.io/dev
- also a free web-based dev environment at https://build.particle.io (I assume/hope this will support the Electron cellular board when it comes out)
I know it doesn't come close to meeting the RAM requirements, but the cellular plan is a pretty big draw IMO. Perhaps worth using this module in conjunction with another board with a better MCU?
-Arthur