In the bay area I've seen quite a number of Heliamphora grown,
many under lights. They seem to do quite well under lights,
the more light the better. They are of course VERY slow
growers, reportedly putting up no more than 4-6 leaves MAX
per year.
I can't say about N. madagascarensis. If it's truly HOT HOT,
then you might find the plant slightly stunted, but then again,
perhaps not. The only highland plants I've grown were N. fusca
and N. tentaculata. The former has thick waxy leaves and
seemed to do ok in my hot terrarium. The latter continue to
be very slow growers, and I now have them outside so they get
cooler night temps. It just depends on the species.
I know nothing about growing Roridula. However I have two questions/
comments: in the CP movie _Death_Trap_, they show a Rodidula species
in habitat. It was quite dry as I recall, and looked somewhat like
a high desert. I don't know what temps it will take, but it looked
like the plant got fairly large.
Robert