Hi Anthony,
No, you can't use Swing designers to produce SWT (or vice versa) because like you asked, Swing and SWT are different types of animals.
I just looked into switching from Swing to SWT. One drawback of SWT is that it doesn't always do automatic garbage collection. I guess it's not that bad though, according to the article in wikipedia, it says
In practice, the only SWT objects which a developer must explicitly dispose are the subclasses of Resource, such as Image, Color, and Font objects
Here's the link in wikipedia.org that I was reading:
Wikipedia on the SWT Toolkit Kaydell
[ July 11, 2007: Message edited by: Kaydell Leavitt ]