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.

I'm going against the grain here and suggesting not buying any Festool sanders, but instead other brands which will accomplish the same and cost half as much or less, especially for home/DIY work.

If you want a larger Rotex then look at the similar 6" Makita, you may need to find a UK retailer but here is the one in the U.S.: http://www.acmetools.com/shop/tools/makita-bo6050j

Also, most brands have quality 1/4 sheet, 1/3 sheet and 1/2 sheet finish sanders. Take your pick. I have Makita 1/4 and 1/3 sheet sanders, and a Bosch 1/2 sheet sander, all of which do an excellent job depending on size of the material or job. I have zero interest in the Festool equivalent products because believe it or not, other brands make excellent tools as well.

Now with all that said, I do have the Rotex 90 because the pad size is somewhat unique with only Metabo (that I have seen) also having a similar product. I also use a 6" Mirka Ceros for large projects, it's smooth and small and keeps going now for 5 years.