@Cerin we eventually used a Teensy 3.2... btw this post was 2+ years old, so Microduino may have changed the product links

This wont work to stop the transmission within a one (or even a few) characters, because although you stopped the Serial.write, there may already be data in the serial buffer (default 64bytes I think in Arduino lib) that could continue to go out (and potentially lost). Anyways, I shifted to Teensy, which has hardware based RTS/CTS flow control, so it is capable of stopping as soon as (i believe 1 character) CTS is deasserted

Thanks Majenko. I do care about compatibility but a better long term solution is a higher priority (also because it will be a learning vehicle for me working on arm uCs). So based on your answer I am leaning towards using the Teensy. Interested in seeing other replies as well (basically if someone has suggestions on boards at par with Teensy in terms of a good board but perhaps with better community support)

Thanks Nathan, good to know someone has tried using 1284 with the existing libs. I want to avoid any major/complex work in porting libs; your comment is helpful here. Also, if you don't mind, can you share exactly which 1284 board you are using?