I have used the Makita GV5000 5 inch disc sander for years. They last me 3-4 years before the bearings give out. This is sanding all day 2-3 days a week for the entire summer. This sander can and will take the work load.
I know exactly how much work you have ahead of you. I paint 2-3 very old houses with very thick peeling old paint every year. I couldn't do a good job without this sander. I need to caution you that this is a powerful sander that will require some practice or risk causing some damage.
I think this is the best paint removal tool on the market. It will save you a lot of time and effort when compared to a orbital sander. Before you go out and buy this sander, make sure the 5 inch sanding discs are available in you area. I use either 20 grit or 36 grit for very thick paint then finish sand with 60 or 80 grit. I have had a hard time finding the discs lately and have to buy in bulk, which is fine for me.