The IR filter helps with colour balance in photographs of the real world. In some science experiments or for night vision it can be very useful to have a camera that also sees beyond the red into the infrared.
In a microscope, however, the objective lens is designed to minimise chromatic and spherical abberations in the visible. Having a camera that can see IR goes beyond the design wavelength range of the lens. This can still be useful in certain circumstances, but for general use the IR filter matches the camera to the design of the lenses.
One thing that would help, if you want to give it a try, is that white LEDs give no infrared light, and IR LEDs give no visible light. So you could use the noir version of the camera with a white LED for the illumination, and the camera is still only getting visible light through the lens. If you switch to IR led for illumination, there is then only a small range of colours, so the fact that there will be chromatic aberration is not a problem.