I am interested in clustering small SBC into the smallest form factor.

Nanopi boards seem to be great option for this as the phy signals come out and can connect transformerless to a suitable switch IC (or perhaps router) with phy signals. The only downside is power is on opposite side to phy so you can't stand board on edge with minimal pins.

I am going to experiment with a couple of nanopi duo.

But in the meantime has anyone else tried transformerless ethernet straight between sbc and router chips and has some experiences to share?

Cheers,
A
PS, look at gumstix stagecoach concept for example.