Just a short explanation for those not familiar with Logic: I and Florian are talking about two different ways of making MIDI looping happen in Logic:
1) Global cycle mode:
One loop length for all loops, loop length for all loops can be changed though.
2) Many separate MIDI Regions:
Regions can be of different length and interact poly rhythmically. This is close to using Ableton Live in Mixer View, but with Logic you see all looping regions graphically in a linear way which makes it simpler to get a quick understanding the periodicity in which loops of different lengths sync their starting downbeat.
One can combine both methods too, as for example Thomas Dolby does in his live show.
After all that trials and tribulations I finally decided to use standard audio looper hardware - an Electrix Repeater and a Lexicon Jamman - and record my synths there.