To help with fast scrolling text when buying I simply scroll upwards a bit. Pauses the text flowing by and then I scroll down and scan through it at a more reasonable pace. I never miss anything on channel that way. I'm sure most people do that, but when I read the OP's comment about the text going by so fast being hard to read, I began to wonder.
As for the split into two channels, no I suppose I wont sign onto that, logical as it sounds. Already have enough people with lack of common sense to simply use the trade channel for WTS/WTB and, no, I dont want to make it more "complicated."
One thing I would like to see though is an adjustment to the display of the Trade channel text. A nice thing about the All Channel is the names are in yellow and the text is in white. On a two line message that wraps, its FAR easier to scan that quickly because you have the name in yellow as your visual key point to where the next message begins. Like a paragraph indent - works the same way.
I suggest taking the names as displayed in Trade channel and making them bolder and a bit brighter. Currently they are not bold and are the same color as the message text on channel and it is therefore a bit harder to scan. It would do wonders for quick scanning of the channel and I have no idea why a designer long ago didnt do that...