Well, first of all I would say that it's not really possible to compare the 2 themes, simply because the 2nd is not a theme, but a wallpaper.
To decide if would be cool as a new theme, I suppose there should be icons, panels and applets.
Speaking about wallpapers, then, I would like the current one more than the second, because it features only smooth gradients from red to orange to yellow. This makes easier to choose colors of windows/icons/decorations/trasparences so they're readable and well integrated in the Desktop Environment.
The second wallpaper catches the attention of the user only to the left yellow and orange circles. I don't know how much this would be useful when adding icons and eventual superkaramba applets/themes.
Also, the first thing I thought when seeing it it was: "It's ugly!". Maybe adding gradients, light effects and so on would make it more pleasant to look
Speaking about themes, instead, I can only talk about the first one.
It's very nice to look, but IMHO the choice to use 2 panels "steals" too much room to the desktop; this could be a problem with screen resolutions up to 1024x768 when making massive use of multimedia applications (and a big trouble when using sequencers and HD recording software). For higher resolutions, anyway, it shouldn't be a problem.
My choice would be to use a Mac-like approach: an auto-hidable centered transparent kicker on the bottom with only the K menu and some quicklaunch icons (for example using kooldock, ksmoothdock, kibadock, etc, so you can use parabolic zooming to make desktop cooler
) and the applications bar moved to the top, so there wouldn't be the actual wasted/unused space on the top-left.