If you get your own PCB's made when the design files are available, you can just fit the components you want, bridging out the RS485 driver will let you still use the serial channel, but at logic-levels.
When I release the files, the PCB artwork will be in a zipfile, just email it to seedstudio, pay the low fee and a few weeks later your very own batch of 10 boards will arrive.
There are refinements I want to make for a next version, perhaps a LED on the board and a reset button. I really want to keep to 1206 resistor/cap packages as for home assembly they are quite manageable, and to keep away from the tiny sm footprints as I just cant work with them. I did have to resort to three 0803 components, the xtal caps and a ferrite bead.
Perhaps some solder bridges for power and 2nd serial options. I'm trying things to see what I can fit.
At this point, I dont have any way to sell these, or even have an idea if people would want them. I made these with my requirements in mind, ie the RS485 port is not a common requirement. I can probably make it optional (bypass the chip) so in that regard its more generally useable.
So I'll just keep on with the testing and trying to fit any modifications I can think of (or are suggested)
I was lucky enough to be one of the Goldilocks backers, I cant wait to get mine.
Its in a completely different class from my effort. It is a very well engineered board and a huge amount of effort and thought has gone into it to make it one of the most 'serious' Arduino's I have come across, suitable for complex and diverse applications, even using the two CPU's for independent programs and communicating between them.
I just thought of the bits I wanted, crammed them into a small space and figured its worth a try... If its a dud then its not the end of the world. If it all works then happy me.
I just like making stuff 