Thanks Wirus, I did get a reply today form the Spanish distributor, he explained:

Of course I can explain you everything as you want ;-).
ProfiLux 3 and ProfiLux 3 eX are exactly (more or less) the same. The difference is: ProfiLux 3 eX has an expansion motherboard installed in it which gives to ProfiLux: 1 redox controller, 1 conductivity controller, 1 "L" socket and 1 Level controller. All the ProfiLux 3 can be converted to eX version by buying this upgrade kit. So you have to remember this: ProfiLux 3 + Upgrade kit eX = ProfiLux 3 eX