Thanks for pics of this trip that you uploaded in the galleries, zen.
The route you took is the normal "inland" route to or from Sani Pass. My own regular choice of "lekhalo" (pass) for crossing over the kaNtuba ridge is some 700m West of the one you took, but this is minor.
Following the escarpment is more difficult, though it does go along some interesting, "forgotten" parts of the Berg. The Tsatsa-la-Mangaung is an imposing, steep barrier separating Sani Pass from Mangaung Pass. From there, the slog up (or stumble down) the slope to kaNtuba Pass is roughly comparable to crossing the ridge further West as you did. Thereafter its an easy stroll along the Sehonghong valley approaching Nhlangeni Pass, from where the ascent of the Thabana Ntlenyana massif from the South-East is roughly the same as what you did. You can also get onto the Mohlesi Ridge and approach from the South-East (little bit longer uphill and no trails).
A variation for loops from Sani Pass would be to access the Mangaung valley via the Sani Flats (as you did), which bypasses the Tsatsa-la-Mangaung, then head up-river towards Mangaung Pass, then up to kaNtuba Pass and onwards. The return route would be the "inland" route as you did (which is quicker).