Is there any kind of gpio board intended for real-time/thetered use, without code reloading or writing my own communication layer?
I have a few designs (Bluetooth & RS232 based) that I customize for my clients. I may be able to help you, but I should warn that my prices are not exactly hobbyist-friendly :-)
It could attract future clients by showing your proficience. And one design would not endanger your paid work in any way :)
I am actually working on a simplified AVR USB board for just this purpose, I'll post it to HN when I'm done.