I am not familiar with either the infared units or the new grinders they sell, however as a painting contractor in another life, I can tell you that there is no easy way to remove multiple (maybe 20 or 30?) from a 107 year old house.

I'd suggest that you try to find a store that deals with the trade and go discuss your project with their staff. I used to use such a Sherwin-Williams outlet in my city and found their staff to be quite knowlegable.

As far as grinding goes the paint you will be removing almost certainly contains large amounts of lead which when ground,at least has the potential to spread contamination over a large area unless properly contained. In addition it will require a high level of PPE for the workers.

I believe that many of the professional contractors use paste strippers to remove multiple layers of paint from wood.

Good luck.