Adding the path to Saxon to a shell environment variable CLASSPATH didn't work.
I assume that this variable won’t be evaluated anywhere. You could have a look into the basex startup script in order to see what’s happening.
Or are you only working with the standalone basex.jar file?
It will probably be the case that I'm going to want to run the transform with either Saxon-EE or Saxon-PE when both are available.
I’ll remember your feature request (but it would require numerous changes in the code, so we might need to collect more supporters for that request).