A few breakout pins, including I2C and a larger servo. Smaller pins are too delicate and fail easily. You don't want two different connector types on the project. Molex Centigrid types are standard for all traditional servos.
I suggest that a "dummy" servo could be used to expand on I/O for lots more pins without the servo and drivers... That is, the same micro controller without any of the motor circuitry but dedicated to sensors, and outputs without the servo case, but using the same power and data daisy chain to be put anywhere in the circuit. Perhaps a Dallas serial number IC to give it a non-programmed address if you don't want to put it's address in firmware.

I would say fewer breakout pins as most projects will probably be using external control systems (arduino, arm, raspberry pie, beaglebone, etc) not the built in microcontoller. Any in most cases you can put a thin cable were you need it... :)

I mean as long as the Moti is the same size as the "standard" RC servo nobody will complain.

Perhaps less breakout pins and a smaller servo. IO expansion via i2c I think would make sense.

smaller pitch pins usually means fragile. I don't like fragile around servos. More breakout pins in larger footprint, within reason is good, but eventually both might be in order?

Love this - looking forward to more!