As to the atium vs. balefire temporal aspect, it would probably depend on the strength of the atium burn/balefire. I seem to remember hearing that flaring atium would give you a larger time jump into the future (can't remember if it was canon or not though . . .) but the strength of balefire can burn things out of the pattern at different intervals. So it would probably just come down to which had a larger temporal distance. (And the average size of balefire is about the width of your arm, if I recall correctly.)
However, another advantage Mistborn have is that 90% of Aes Sedai have to use hand gestures to get their weaves to work properly. Burning atium would let them see which hand gestures the Aes Sedai was using, giving another insight in to what the channeler was going to do.
As for zinc and brass, while channelers don't need complete emotional control, they do need to be able to focus. A Mistborn could riot emotions such as shock, worry, absentmindedness, or some such to weaken that control, or soothe all their emotions away in a big push to shock them out of weaving right. Of course, where Aes Sedai are trained to handle their emotions, this might not do much good once they figured out what was going on, but it could be used to stall and close in.
And as for Mistborn not having good long range attacks against Aes Sedai, it may be true, but a steelpush or ironpull (enhanced with duralumin perhaps?) would considerably shorten that distance very quickly. The terrain would really make a differene in a fight between the two though, as a lot of factors come down to how much metal the Mistborn has to use and how fast the channeler can get a weave around them.
Also, most Aes Sedai keep coins on them, don't they? A Mistborn might not have to get too close if they can just push the coins off them far enough to pull them back with lethal force. Aes Sedai aren't likely to guard against their own coins killing them. (Though I bet they'd learn fast.)
And keep in mind, it takes quite a lot of the One Power to go moving earth around, particularly large amounts of it. While the Aes Sedai in question could probably do it, (a touch unfair to give the Mistborn advantages such as atium and metal to work with without the Aes Sedai being equally gifted.) it would take quite a bit of effort to encase someone in stone. Which raises another question. Could a Mistborn riot/soothe an Aes Sedai's emotions to make them more likely to draw on too much of the One Power or otherwise let it consume them? I would think they could, as Rand makes Saidin at least sound easy to fall prey to.