Detail in reds, well yes ... but subtle hue differentiation within anything categorized as a true red (vs orange) is another story. By the time of
Ciba II ("self-masked") and later Fujichromes (and alas, ownership of a true additive colorhead), I had pretty well tamed it. But by then I had
also learned a lot of specialized masking techniques. But I've only done about four Cibachromes in my life where red was the dominant color in
the composition, and each time it was a fairly faithful representation of the chrome. ... Masking with color negs is soooo different... more like
gentle power steering rather than slinging an iron ball at a brick building! The most common Ciba mask for a scene containing both saturated
green and red was made on pan film with a deep magenta 33 Wratten. Then you could vary this a bit one direction or another by resorting
to a 34 violet or 29 red the other direction, etc. This pegged the G vs R saturation (an oversimplified explanation)... then you pegged the
Y vs B via bleach activity, which altered the behavior of the "self-masking" feature. The procedure with older Ektachrome 64 or Kodachrome
was slightly different. ... sounds kinda complicated, but it was actually a lot of fun. With current Kodak color neg films the masking game is
mainly just up or down contrast control, though one still has to establish a neutral first base position or there will be a hue bias. The big trick
there was to develop an extremely low contrast straight line mask - and I do that with very dilute HC110 and TMX sheet film, with a pinch
of benzotriazole toe cutter. The result is quite a bit better than the old Pan Masking film.