To update: So far, everything looks good. Using USB3 and external SSD disk is "fast enough" for many purposes, and when needed, the whole setup can easily be transferred. I have also found that even with USB2, the performance is good enough at least for testing when running with a generous amount of RAM.

On a HP notebook, a kernel bug keeps cropping up keeping one of the cores completely busy, but the remaining three cores are able to run services nonetheless. As this is not something to live with in a testing situation, it is very practical just to hook up the SSD disk to another machine not suffering from the bug.

One uncertain thing right now, is the best Java version to use. Knoppix comes with OpenJDK
Code:
 
root@Microknoppix:/store/KNOPPIX # java -version   
java version  "1.6.0_18" OpenJDK Runtime Environment (IcedTea6 1.8.7) (6b18-1.8.7-2~squeeze1)   
OpenJDK Server VM (build 14.0-b16, mixed mode)
I think I will give it a try, as it seems to be compatible http://www.jboss.com/products/platfo...onfigurations/

But my synaptic can't tell me of any jBoss 5 .deb-package yet, so I think I must use a tarball for that.