The Office Mill is nowhere near your 20" by 16" travels. Haas MiniMills are 16" by 12", the smallest VF is 20" by 16". Spindle speed of 10,000rpm is an option and higher is possible but then you must sue balanced tooling. I have found Haas machines are repeatable to +/-0.0001" or better, which is what they claim if their literature. If you are hogging out big steel castings a small high speed spindle Haas machine is not the way to go. Similarly if you want to work to a few microns in a temperature controlled environment with the machine mounted on an islolating foundation these are not the machines to get but for ordinary tolerances they are good value for money.