Backgas is MK25's with S600, best hose routing and nice compact regulators.
For stages DS4's with atx50 (hard to get these days I heard). I like these better, lower breathing resistance, impossible for me to free flow and very easy to service. Unforunately I like the hose routing not as good as the MK25's.
Still having some doubts about switching completely to apeks but house routing and lighter (for travelling) keep me thinking...
