Your quite correct schweb, Transmit is a great piece of software. However, it has a few obvious flaws and has a much less robust editor than what is promised and so far shown in the many screencasts that extendmac has released for flow.
I'm not sure if it still exists, but a while back there was a video of a side by side comparison of Flow and Transmit, and Flow won in upload speed by a long shot. The way he spoke about things he admitted he had somewhat of an advantage because it wasn't finished yet and he was very quick to say that the results may change.
He also points out a few features that Flow has that Transmit does not. I'm not trying to advertise and I am not affiliated with Flow in any way, but I have a feeling Flow will be a much more superior FTP program than Transmit.