Ah well, yes this should work at least for updating only single operators. The same way, if somebody else is interested, it is probably also possible to downgrade to the old NN learner by replacing the classes in the 4.4 release by the old classes and also replace the file joone.jar in the lib directory by that of the 4.3 release.
Thanks for the hint.
Well, I hope I get no problem with other modules, but with this I can wait until version 4.5 is released ;-)
But please don't forget to send in the answers for the delay questions while working with the 4.3+ version ;-)
All the best,