Partly correct about the nature of detached vortices at high AoA with a 'slender delta' (i.e. Concorde), but a ram's horn vortex is a differnet beastie not merely associated with delta configurations. Movies of Concorde flying the approach on humid days show the vortex pattern quite clearly.
In the tin triangle, I don't recall any minimum speed at altitude apart from Vapp minus 5 when learning low speed handling quirks with an OCU QFI. Flying slowly at height could leave you unable to accelerate back to normal cruise speed if you flew too slowly. We found this out one day when 'Watt the Plot', our infamous Nav Plotter, requested a speed reduction in order to make a LL entry point time in the south of France after we'd encountered unusually strong winds. Back to 190 KIAS at FL410 for a while - then it wouldn't accelerate out of it even with max continuous. So the Capt sheepishly asked for an early descent and all was well again!
A shame that Skippy killed off your magnificent rocket ship so prematurely, Bellerophon!