I have yet to see any microcontroller that wouldn't guarantee its GPIOs (unless they are output only) to be in Hi-Z state upon reset. If they weren't, most designs out there would fry, and having to protect them from this issue would be extremely costly overall.
Modern µCs IO's can drive several mA of current (source and sink) and their input capacitance is usually in the order of 10-20 pF, so unless you're aiming at the 100 MHz+ frequency range, you're not likely to have any issue faning a single output out to a dozen inputs.
As suggested above, series resistors (depending on the data rate) are a good idea to lower EM emissions.