Well, after a new starter relay, liberal application of DeoxIT, and a new ground wire direct from the battery to the topmost ground above the starter (a strand of solid copper from a romex bundle), she now seems to be firing up every time (so far, anyway...). I may not do the bypass switch (yet...).
The Stelvio's don't do startus interuptus like the Breva's, if it doesn't start something is wrong on parts or connections as on any motorcycle that doesn't start. My 2015 NTX has a Chinese starter, not a Chinese Bosch. Just like other Guzzi from same building year.