If you can hold on a bit longer, I'd suggest waiting for the Gigabeat X series, which will be available in 20, 30, and 60 GB capacities. It's been out in Japan for over a month already, but judging by what happened with the current F series, it probably won't make it over here until sometime in the middle of next year. I've seen some available for purchase (imported, I guess), but it'd cost you $400 and no warranty (it will be more like $300 when it makes it over here).
The Gigabeat X20 and X30 (20 and 30 GB, obviously) are 20% smaller than the F series in every dimension. To compare it to the 5g iPod, it's shorter, narrower, a tad thicker, and a hair lighter. The X60 is a bit thicker than the other two, as expected. It has an even bigger screen (2.4 inches), and the plus touch controller seems to be improved; it is now raised slightly above the surface instead of sunken in. It also supports USB mass storage class, so you can drag and drop stuff right to it from your computer instead of using proprietary software.