Sorry for the late reply. The Arrakis and Altair are very similar in design, they both use the same composite cabinet construction materials and the driver / internal crossover technology is based on the same design. The Arrakis is not any more technically advanced than the Altair, the main difference between the two (other than size and number of drivers) is that the Arrakis has an active crossover which allows you to attenuate the lower frequencies, also the Arrakis is bi-amped which has some advantages. The Altair uses the same drivers as the Arrakis, just not as many.
As far as nearfield listening, or using the Arrakis in a smaller room, in my opinion it can work well and will actually achieve better results than the large Wilson's due to the linearity in the bass region and having the ability to attenuate the bass through the outboard active crossover which has separate left and right controls for this.
I recently setup a pair of Arrakis in a room that measured 14'x37'x9' wlh. We have them on the short wall firing long. (I will post some pictures shortly). The sound is very good, but these larger speakers like the Arrakis move a lot of air and having volume in a room does help them relax and sound their best (the active crossover on the Arrakis helps here). Also, mathematics has a lot to do with the end sonic result - like the room mentioned above that measures 10x12x8 is not the best dimensions mathematically. Of course there are other factors involved in room acoustics and it can get complicated, but with proper setup and minimal treatments good results can be found.
For conversation I would define a room that is less than 200 square feet as small. 200 - 400 square feet as medium and anything over 400 square feet as large. If it were me making the purchase, I would purchase the speaker that will ultimately be in my permanent listening room. In other words, if I knew that long term I would be in a small room, I would purchase the Atria or Avior. In a medium to large room the Arrakis or Altair would work nicely. Every room is unique (volume, dimensions, construction materials, shape, treatments, ect...) but if the room was small to medium sized, i think the Altair might sound better than the Arrakis due to the rooms volume and its ability to handle the amount energy and air being moved.
I looked at Roysen's room dimensions and without seeing the room in person, I think the Arrakis or Altair would work well since the room has decent volume, even though it is L shaped. But the Altair would be really sweet too and would probably be my choice.
Hope this helps.
I'll post some pics soon.
Ken Boyce
Cake Audio
California USA
Authorized Rockport Dealer