I bought a similar machine when I needed to sand about a thousand feet of cherry trim for our house and now find I use it on pretty much every project that goes through the shop. It's ideal for precise thicknessing of thin stock (for organ pipes in my case). So yes, a machine like that is a great addition to the shop. However, without the conveyer system, I wouldn't buy that one unless you really like difficult and expensive refurbishing projects.
Knowing what I know today I would have opted instead for a small wide belt sander instead of the drum sander. Changing grits on the drum sander is a fiddly and unpleasant process. The flat belt make that task easy and also avoids the problems with the spiral wound sandpaper shifting on top of itself and creating a high spot that burns the work.