Tourer: Stock shocks for occasional two-up riding, 425# with gear in saddlebags and T-Bag = perfect. Stock shocks for solo riding, total weight 255 with gear in saddlebags with no pre-load adjustments tends to be just a tiny bit bouncy.
Though I'd welcome a test ride on a similarly equipped Tourer with after market shocks I don't know what the fuss is all about with the stock shocks. One thing about Alabama roads, aside from no shoulders as a common attribute, is the condition of the pavement is above average. Now the CSX railways crossing are another story. I think it's all about total carrying weight factor. A light weight on a Standard with the same OEM shocks may be too much even when ratcheted down to minimum pre-load.
"ONE concise, (THANKS) authoritative and potentially universal prescription..." = Stock Shocks: because Triumph is authoritative and have installed a universal prescription.