The NEMA23 motor has a higher current and holding torque, which can be advantageous for wood machining tasks. However, the NEMA34 motor has a lower inductance and a higher holding torque, which could also be beneficial. Regarding the shaft size difference, going from 8mm to 14mm with the coupler might raise some concerns about compatibility and alignment. Also, if you're feeling adventurous, you can even roll a d20 roll. using a dice roller to add some randomness to your decision-making process!