I'd have thought that whether you upgrade the OS or not you should try
to pick off the particular problems one by one as 4.04 was always very
stable on my Kinetic Risc PC. I wonder if the instabilities are caused
by software other than the OS version.
RISC OS 4.39, like 4.02 (SARPC) and 4.04 (Kinetic) was particularly
thoroughly tested because it was placed in ROMs.
I have 4.39 ROMs in my Kinetic Risc PC and found the stability of the
machine was much the same as under 4.04.
The exception is if you have a viewfinder card.
The Kinetic/Viewfinder combination was not usable on my machine under
I'm told that the latest version of select has resolved these issues
with Viewfinder but I have yet to update to this on my Kinetic or
reconnect my long disconnected (because of the 4.39 problems)