This thread will not turn into yet another "what is SFF".
Why not? If it's civil discussion, why moderate it? There's nothing wrong with reevaluating things from time to time. Declaring SFF to be 19 (or 20) liters, period, is not only a completely arbitrary line to draw, but needlessly shuts out discussion that might be of interest to a lot of people who are interested in small form factor. Not to mention it also feels a little elitist. Are we really not going to allow people to post their Cerberus X builds in the build log forum because it's a hair over 20L? That hardly seems reasonable.
If it were up to me, the only verboten (or OT) things would be those that couldn't reasonably be called SFF by any stretch. That's a definition with a lot more leeway, which could easily include cases closer to 30L, as long as they used the space efficiently.
Yeah, if i fill up a Cadillac Escalade with 2 houses worth of furniture, filled to the last square inch, its still not a compact car. Whether or not all the space is used efficiently, the sub 20L rule makes sense to me. Its Small Form Factor, not Space Effecient Factor.
Well, there's a whole lot between a Smart and an Escalade. But to get away from the car analogy, a 25L ATX case is certainly small when compared to the typical 40L+ ATX cases on the market. If you can answer, "relatively speaking, is this small?" affirmatively, than IMO it's certainly within the spirit of SFF.