When I say "final", what I mean is that I think I finally have come to rest upon a coherent and satisfying position but probably will end up changing it again at some point in time, whether that be by my own admission or by a critique from another individual.
Anyway, here goes!
The first point to be made here is that I believe pleasure to be supererogatory. This means that the lack of pleasure is not a bad thing in itself. However, what I think tends to get looked over is the fact that even if the lack of pleasure is not a bad thing, the presence of pleasure is surely a good thing.
Now, many times the lack of pleasure is accompanied by a feeling of deprivation. We often feel desire for a pleasure and a sense of being incomplete without it. This is a kind of "suffering". But pleasure is not what eliminates this suffering - what eliminates the suffering is the act of obtaining pleasure. We can also eliminate this kind of suffering by focusing our attention elsewhere.
Pain is pain. Ignoring the cases of masochism and BDSM, I think it's pretty damn obvious that pain or suffering of any kind is a bad thing. Hopefully this isn't a controversial point.
Now, Benatar states that the lack of pleasure is only a bad thing if there is someone that can experience its deprivation. I'm apt to agree. However, he goes on and says that the lack of pain is a good thing regardless of whether or not there is anyone actually there to experience the relief. There are some issues with this. I will attempt to break them down:
First, I do not usually proclaim that it is a good thing that I am not experiencing a headache. It's only apparent that this is a good thing when I compare myself with counterfactual, possible me's. In which case, the real me who is not experiencing a headache is not in a good state just because I'm not experiencing a headache - I'm merely in a better state than if I were.
Second, if we are to use counterfactuals for pain, then we really ought (and need) to use counterfactuals for pleasure. For I can imagine myself experiencing pleasure - in fact, this imagery is often the cause of desire (which causes suffering in some sense). Regardless of the fact that this imagery causes suffering, since pleasure is good then a possible me experiencing the pleasure is better off than the actual me who is not. This does not mean that the actual me is in a bad state, though, just as the lack of a headache does not mean that I am in a better state.
Third, counterfactual, possible if-me's do not hold the same good-ness or bad-ness that actual me's do. This was already explained above. For example, we typically don't throw a party because someone avoided a really, really bad situation - we throw a party because a person is experiencing or is about to experience a lot of pleasure. And we typically don't mourn the loss of pleasure - we mourn the subsequent gain of pain.
Because of this, I believe that if we are to use counterfactuals for possible unborn people in regards to the pain they will experience, we need to use counterfactuals for the pleasure they will experience.
Now, like I said before, I think pleasure is largely supererogatory. So it's intuitive that the lack of pleasure is not really a bad thing. But the trouble is that Benatar holds that the lack of pleasure is not bad if there is nobody there to experience the deprivation. But if there's nobody there to experience the deprivation, then how can we possibly say that it is a good thing that a person is not experiencing pain? There's nobody there to experience the relief.
Furthermore, like I said before, Benatar conflates the "good" of the lack of pain with the GOOD of pleasure. His entire argument hinges upon his equivocation of the two. He specifically states that it is difficult to calculate how much pleasure or pain someone experiences (and yet he goes on later to explain why our lives are really bad which is calculating pain but whatever). Because of this avoidance of calculation, Benatar avoids the issue that would break his argument apart: that we often do plan things to do based upon how much pleasure or pain will be experienced. Benatar openly embraces the idea that a pinprick disqualifies all pleasure by making the "good" of the lack of a pinprick equal to the GOOD of a million orgasms. He also seems to ignore the fact that even if pleasure is supererogatory, it's still good. He's appealing to states of affairs without considering the composition of these states of affairs - I liken it to saying there is flour in the cookie mix without actually stating how much flour is in the cookie mix. All Benatar is concerned with (at least with his formal argument) is that there is pain in existence and no-pain in non-existence without actually considering how much pain is in existence and how much pain is avoided in virtue of non-existence.
So in conclusion, I believe that Benatar's asymmetry, although being intuitive, is not logically sound. The intuitiveness of his asymmetry is derived from his material argument and other evaluations of pain and pleasure.
Ultimately, I do not accept Benatar's asymmetry, although I do accept the conclusion of it. More on that later though. I think I've enough deconstruction for a while: time to actually construct something of my own.