are KDE 3.3 (sarge) and KDE 3.5 (etch) configurations compatible?

[Johannes Wiedersich <johannes@physik.blm.tu-muenchen.de>]

We have home directories on a central server (mounted via nfs). Having 
several sarge workstations and one (or for that matter several) etch 
workstations.

If users alternately log on and off either workstations (one at a time), 
will there be conflicts with configuration files? Ie. will there be 
problems, if I open ProgramX on etch and later open ProgramX on sarge 
(previous program version)?

Is there a simple way to keep sarge's and etch's user configuration 
files out of each other's way?

I don't expect problems with Openoffice (.openoffice vs .openoffice2).
I do expect problems with firefox et al.
What is the situation for kde-programs and gnome-programs?

Any recommendations?

Thanks,
Johannes