This time is different because, we are using even more FSX-only features (like 4096x4096 textures and 2048x2048 detail textures), that we can't do the scenery in FS9 without lowering the resolution compared to the other FS9 sceneries we made so far.
As we already explained, we don't know how this will be noticeable, without trying first. We will surely try, but we can't guarantee the end result right now, because we don't know yet. We will know when the FSX scenery is finished. The general idea is that, if it's visually worse than the 4-years old Cloud9 version, it might not be worth releasing it.