To answer the questions, you need torque if you want your CNC to be fast. Otherwise you will end up doing thousands of small passes at low speeds, and every part you’ll wish to cut will take hours. Since you cannot really leave a CNC unattended, this means that you’ll have to spend these hours watching it in the noise and the dirt. No need to say that you’ll end up hating it quickly.
So In my opinion, torque is key if you plan on using your CNC more than twice a year.
If you want a fast CNC, you’ll need two things: a powerful spindle with a good bit and powerful step motors who won’t stall or miss steps.
Since you already have those motors, I would recommend you to use them and try by yourself. If you find that they are not powerful enough then it is quite easy to change them later.