Actually, they're not all highland plants. Macrophylla is a highland plant, and so is jacquelineae. Platychila, however, is a true intermediate, being found at 900m to 1,400 m, so it doesn't need the type of night temperature drops as true highland species. Macrophylla, as noted, grows quite rapidly. Jacquelineae is much slower. I don't have much experience with platychila and we only have seedlings from Rob so they're way too small to give any reliable data on, but given it's altitidinal affinity and it's location, it should grow at much the same pace as vogelii, which is reasonably fast. Jeff Shafer would be able to give you substantive views on that one.
As for humidity, all Nepenthes like high humidity, some are more temperamental than others, but humidity is a key ingredient to success.
Anyway, I would not lump these three species into the same basket.