But then I'm going to end up building two power supplies in one instead of one which the 3D printer module just splits into two separate power channels...right?Linear is way more forgiving of current and power spikes than SMPS based systems are. As far as heat goes it's only a problem if you designed the circuit wrong and used way too small of rated devices and heat sinks.
If the primary load is almost all motor driver power then the voltage and current filtering is even less of an issue and a simple transformer to bridge rectifier to good old heavy capacitor bank is more than sufficient and clean enough and the dedicated more sensitive logic circuits can be ran off their own independant regulated power supply so they are isolated and for the most part immune to motor driver related noise.