I did the same thing. Actually it might be better because of the way the 3D model was created with the air vents. Essentially the airflow is directed out the sides and it works incredibly well.
I have been carving PCB’s for the past few weeks with this setup and it’s incredibly accurate.
BTW the Makita I think is quieter than the stock spindle at lower RPM. Having said that once you wind it up to max it can be quite noisy.