More space in folders - I am not complaining, I am giving my voice of what should be in iOS6. Not hard to understand. If don't use your devices as much as I do, don't force your limitations on me.
Folder Sync: As far as devices, I have an iPod touch, an iPhone and a couple of iPads and may add another, whether I "should need" them is frankly not for you to decide. Most apps do go on all devices and at least that's a start. At a minimum I should be able to set up a profile and restore it to a device. When I change out iPhones at this point I have to redo all my folders, that alone shouldn't happen.
Siri Voice: Gimmicky? Half of everything Apple does is gimmicky. I'd rather have Siri with a new voice and accent than Photobooth.
I'm not sure how you wanting to have 16 apps per folder as opposed to 12 means that you use your devices more than me... but aside from that, my point is that there just isn't enough room on the current iPhone. Open any folder with 9-12 apps and you will clearly see from the faded out apps that there isn't enough room for another row. You can argue Apple should squeeze them a little bit closer, or maybe by removing the rudundant space there may be enough room, but I personally think (and obviously Apple agrees) that would look a little crowded. Also, I like the size because you can press on the empty space above OR below the folder to "close" the folder. It's a subtle thing, and you probably don't even realize how much you appreciate it. My point is Apple made the folders that size for good reason, and I don't see them changing it. Now a 4" iPhone 5 on the other hand...
You're right, it's not up to me to decide how many iPads you own... but what in the world would be the purpose of one person owning two iPads mirroring the exact same apps on each one?
I don't even understand the need for two iPads (or an iPhone and iPod touch for that matter) for a single person, but I won't question your uses. Also I was almost positive that if I restore my iPhone from my back up it keeps my folders... If not, then I agree that should be added, but that's simple enough.
Well my point about Siri is that there are a lot more improvements that can be made, different voices should be low on the totem pole. For what it's worth, I doubt Apple would ever give Siri various voices simply because they probably want Siri to have one easily recognizable voice. Of course that's not a reason against why Apple SHOULD do it... but just my personal opinion on Apple's philosophy