Massive air extraction also means you’re pumping a lot of heat or AC out of the building. You want enough - but not too much! Thunder sells similar blowers as what we are using. What helps keep the smoke from exiting into the room is to leave the door closed for the 15 seconds the blower runs after the machine stops cutting!
Also, systems with closed, fresh air pressurized laser paths (to keep the mirrors clean) require massively expensive air filters so the air that gets pumped in is completely dust-free. When I talked to the guy at Dragon Laser (who has lasers that use this type of system) he mentioned the replacement filters on that system were many thousand dollars EACH and the air filtration system was many, many thousands of dollars to start with.