My composition workflow is based on loops - starting by creating rythms in Hydrogen and recording a few drum loops in Ardour, creating a bass line with amSynth or ZynAddSubFX and recording a few bass loops in Ardour, recording some guitars in Ardour and creating some samples from that...

The difficulty I'm having in Linux is to create composition from those loops.
In Ardour is is time consuming to reorganise the loops to test new order/composition (because Ardour is not meant for that).

My idea of a workflow would be to have a tool to try out the different loops in different order and "jam" with them to see what works and what doesn't.

Non-DAW has better features for dealing with looping regions/clips than Ardour does. You can set a loop point on any region, after which adjusting the region length adjusts the number of repetitions.

I quickly cheked the feature list for Non-DAW on their website.

Although the feature you described is listed, it doesn't really say if it eases the composition part. It looks to me like you need to have a clear idea of the song structure.

What if you would like to try out different arrangements quickly - can you confirm or infirm if that is the case?