To my last posted Asynchronous Device Platform code I added a sound sensor and an I2C three axis accelerometer using a SeeedStudio ADXL345 library and the standard wire library to my project. The framework handled the additions with no problems. This brings the total to 3 analog input sensors, 2 digital input sensors, 1 I2C sensor and 4 digital outputs for a total of 10 asynchronous IO's. The sketch takes about 14K SRAM and it ran fine with a time tick of 2.5ms but crashed at 2ms.
At this point I believe I could reliably operate at 3ms time ticks with at least 10 I/O's spanning digital, analog and I2C bus. The only Con I can think of at this point is that I could run out of timer interrupts running on the 328P. In this case I would need to move to a processor that had more timer interrupts, read more expensive board. The Seeeduino board I'm using now costs $22.
So unless something drastically changes, I believe the Quantum Leaps platform will make an excellent base for my ADF platform to support my projects.
project files are here