i am using the ELAC UniFi Slim BSU5, it has essentially similar specs as UB5, as suggested by the manufacturer. It is bit smaller in size with extra colour options. The sound signature is same for both. From personal experience i can tell you that these are power hungry speakers and you need a powerful amplifier. I am using Crown 1502 to power these speakers & it drives them well.
If you are going for a stereo setup i will recommend something like NAD power amp, given that you are in germany. I am myself considering this power amp and possibly hypex500 based amplifier as an upgrade but have not heard them as yet. Extra headroom for driving these speakers always helps.