I do agree that there is much wasted air space in most of the caps. And I do like the design of the deeper well just the positive of wicks "swimming" in the well; almost tank like. The now, only, solution/compromise for this is the Surface. It has a well, similar to the A7(s) and bottom attachment air intake, and has a reasonably short cap. In addition, it does have a (what looks like) delrin grommet in the cap to keep the excess juice from leaking out even when PV turned up side down. For less than $70 mailed, it looks like the closest thing to "perfect" we are going to find. (Just think about how many RBAs you are going to try before finding "perfect.") Some of us will know in a week or so when they arrive to US and are delivered. ChrisEU, from Germany, has already received his.
Feisty Alice