They were added over time and resulted in improvements, As mentioned, I tried to optimise the setup for each scenario individually.
Feet One-o-0ne
Somewhat reluctant to write about this topic since all speakers, rooms, acoustic treatments and distances/dimensions differ and everything has a bearing. Furthermore I am reporting on my experience with Duevel Bella Lunas, which as omnis have their own characteristics. All comments relate to the speakers being set up in the respective sweetspots which depend on the footers resulting in individual adjustments up to several inches. Room decked out with heavy carpet, bass traps and sound panels on ceiling and side walls.
Anyway, the journey started with spikes which compared to the bare bones added better ability to locate instuments in the soundstage but otherwise reulted in a somewhat sterile, bloodless rendition.
On to ball bearings (Final Darumas, similar to rollerblocks): better integration but slight wallowing in the bass.
On to Symposium Svelteshelves: good soundstage, great integration albeit at the price of slight congestion in the lower mids.
Svelteshelves on ball bearings: better location of instruments in the soundstage, clear midrange, slight loss of deep bass (may relate to added distance from floor)
Finally spring bearings (Matihur on AliExpress): Shazam, everything snaps into focus, great integration, crystal clear deep bass and increased detachment of the soundstage from speakers.
Mahgister and MillerCarbon got it right: best solution for my system as well, total absence of undesirable side effects and all of that for less than 50 bucks. Very highly recommended.
Final warning: YMMV