what you are referring to by Serial Polarity tho.
If you want to connect two devices (especially two that are the same such as two of these boards) you have to swap Rx and Tx. In the past I've found the easiest way to do this is with a 2x2 header and two jumpers. The jumper are say horizontal for one polarity and vertical for the other, so there's no wiring of special plugs/cables. The alternative is to have crossover cables. With Pololu-style discrete connectors that's easy enough, but with ribbon cable you can't (easily) make a crossover cable.
However if you're not using ribbon cable this is all pretty moot. It's easy enough to wire up a crimp connector in any format.
It's largely an aesthetic thing for me, if you use separate wires they look ugly and you have to have a huge DB9 shell with just 3 small wires poking out the back. Ribbon cable looks neat.
I've had no luck finding a 2x2 crimp on type for a ribbon cable.
You won't AFIAK 2x3 is the smallest.
I couldn't find a 2 pin header that was just pins.
Do you mean in the Eagle library?
OK, I get it.
The SD sockets now line up as I would have expected. How far out does the card sit physically. I'm guessing that's what those lines are but there's 3 of them.
What I'm getting at is accessibility when the board is in an enclosure, any memory card has to poke off board enough to be usable from outside the box. The right most line looks good, the other two would not work. Are there 3 sizes in micro SD, I didn't think so. Not that there's much you can do about it, the socket is already right on the edge.