Without knowing exactly all the different DPS rotations and only knowing what I know as a level 50 DRG, I would feel DRG is better suited to have Balance versus Arrow because of the amount of oGCDs they have that do nothing with Haste and I would have to respectfully disagree with your assessment. They'll still be able to make use of it, but I feel the 3% Haste is better for NIN / MNK / WAR than it is for DRG. Also, take into account any mechanic that reduces the effectiveness of your Selene buff will also reduce the effectiveness of your AST buffs too, especially if said buff is Extended / Time Dilationed. Most A1S parses I've seen have their DPS clocking in at around 800-900 DPS which means Balance would probably give an individual somewhere between80-11040-80 (edit, realized my internal math was slightly off since full time Balance = 5%) assuming perfect RNG. I feel the upper end limit would be higher just because there's a lot of downtime in the fight with movement and gives AST time to set up good combinations when the Oppressors are in the sky.
Also about the Adlo comment, yeah, I can agree with that. However, if you're a good SCH, you're hopefully never putting yourself in a position where you're relying on Crit Adlo + ET to live through something ^^;
As a random aside, I appreciate the amicable discussion on the whole thing. It's quite refreshing compared to some other discussions.
This is actually why I like AST so much, is because you just don't know. Would I have Balance on spread and looking for the RR? Would I have Enhance on RR and looking for the right? That's the nature of the AST beast and it's fun to play the job on the fly as it is. You may have all the pieces lined up already and you may not but the DRG in your raid told you "Hey, my B4B is about to get off CD" so you make a decision there on how to proceed. I know it doesn't answer the question, but I'd like to think there are equal amount of opportunities where the card lines up perfectly and other times where it just blows up entirely in your face.
With that being said, while it's true none of the buffs are bad, certain buffs are certainly more desirable at specific instances of the fight. For example, you begin a fight with Faust (Savage) and you pop Expand Balance that was setup to give everyone a strong boost at the beginning. You Draw into your next card. At this juncture, Ewer and Spire are both not necessary (but can be RR'd), Spear won't be useful because you want everyone to maximize their CD usage with the current Balance (can also be RR'd). If you get Bole, you can RR that for Enhance or save it until just as Balance is about to expire and apply Bole on your tank. If you get Arrow / Balance, you can also save this and give it to a DPS once the existing balance is about to expire.
Notice how three of the cards in this scenario mean very little and the other three are very useful? Desirability of buffs is dependent on what is going on in a fight and when you happen to Draw that particular buff. While RR does mitigate the less desirable cards to a degree, if you're lining up for something specific and both your Spread and RR slot are filled, you may find yourself in an bad position of wondering how to play your next card. While clicking off a Draw is always an option to start the next draw cycle, something feels wasted when you do that since now the CD is gone.