It's me again, DrD, before you decide, look at what sand paper cost and selection you have with the round sanders. As I said earlier, I have 3 round sanders, and the half sheet RS2E. I do a fair amount of sanding (all connected to CT26 dust extractor) and nothing I've encountered yet couldn't be taken from rough finish, for example reclaimed barn wood, to 1000+ grit polish using only 1 sander, the RS2E, or its Bosch and maybe Makita (not sure if Makita makes one) counterpart. And, the paper cost is way cheaper/less expensive!
If I were to have only one sander, it would be the RS2E - although the RAS115 is handy for scooping out chair seats.