I have measured both the Stagg and my DB and the stagg has approx 10cm extra length behind the bridge, the scale length is about 5-6mm longer than the regular upright. Thinking out loud here then, so if you fit 4/4 strings designed to be weichs to the stagg the shorter scale length will make the strings floppier than the manufacturers intended so a set of 4/4 starks might give something more like a medium tension and mittels more of a weich tension, weichs then not being suitable. I have 3/4 weichs and they work well, lighther to play than my DB but not flappy or rattling etc.
Hope that makes sense?