Is this the one Decware is selling?
This would appear to be the new Decware special 1.5 way: http://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1480053076/30
My calibrated eyeball says it is 9" wide, 12.5" deep and 35" tall including feet. I estimate an ~40 liter volume, roughly twice the volume of a Super 3U or XRS and would give each driver the equivalent air volume. I would imagine the larger enclosure will maximize the bass we can expect from an RS5 driver.
I'm still not 100% sold that there is no tradeoff in going with a larger enclosure for RS5 driver. I remain of the opinion (with no real basis other than gut feeling) that there is a sweet spot for each driver between deep bass production and midbass snap. In the case of the RS5 driver, that sweet spot may be around 20 liters per driver. That's what is in the Super 3U and Super 3XRS. In this new 1.5way floor stander, we are seeing a similar volume per driver. I haven't seen the rear of this particular model, but I would imagine it to have two ports as well, matching the tuning of the XRS.
A 40 liter volume seems about right for the cone area of two 4.5" drivers. The Super Alnico Monitor has about twice the cone area in its 6.5" driver and has a similar volume (36 liters).
I recall the bestselling Snell speakers from their classic Peter Snell era being the Type E and EII. These were medium sized (about 50-60 liter) floorstanders with an 8" driver and 1" tweeter. This same driver complement was also implemented in the smaller Type J (~40l) and Type K (~25l). These latter models were targeted at a lower price point and sacrificed bass quantity for cabinet size. However, it is possible that one of these smaller models was more optimum for the driver used if absolute bass quantity were ignored.
The RS5 driver appears to work successfully in volumes from 9 to 20 liters.