What we're seeing here is the product of highly skilled and experienced growers who know how to treat the plants so that they can flourish in conditions divergent from their natural environment. That being said, San Diego (and most Mediterranean climate-regions where people grow Neps outdoors successfully all year) still has the nightly temperature drops that people claim these plants need to survive. It's a far cry from a dark windowsill in Chicago handled by someone who reports experience only with N. fusca and N. alata.
If you don't have the temp drop, the plants grow too fast and exhaust themselves. If it's going to be super hot, feed the cold growing HLs and UHLs a lot to get them through it. I had my villosa survive 90+ degree temps outside before, with a drop to just 80 at night, but I did make sure it got lots of food. The poor thing. Sometimes I stick it in the fridge over night.
I also had success in Vermont, window sill growing ventricosa, sanguinea, and ventrata. I didn't stay long enough, after picking up the hobby, to get more plants there, but it is work-able. The snow helps to reflect the sunshine in the winter. I also had some Theobroma Cacao (chocolate), and Lemon trees growing. Then just the regular old houseplants too.
I think with neps based on my observations for the past 6 years, they need a certain amount of sunlight hours in order for pitcher production to occur, they need humidity in order to grow quickly and make bigger pitchers, and all of them other than UHLs don't like dips below 60 at night otherwise they stall until it warms up. And then the temp drop of course. I started with the plants suggested in Nepenthes Around the House as outdoor plants, intermediate and above, and experimented from there. I determined even some of the intermediates don't want to grow outside for the occasional chill even in San Diego (e.g. N.platychila I think would like indoors better over the 'Winter' months). Most of Neps can stand the low and swinging humidity, but there are a couple I've encountered that really won't stand for it and start shrinking and threaten to die (e.g. N.hamiguitanensis). And most can take the intense and numerous hours of direct sunshine but again, some won't grow in it (N.ovata). N.edwardsiana doesn't seem to be in any of these categories so far for the couple of years I've grown it, so I would suggest it as a beginning HL plant actually. It does grow kind of slowly though.
BTW the best plants suited for the climate here all things considered are Trusmadiensis crosses. They grow slowly, but their pitchers don't mind the swings to 0 humidity for days or weeks at a time, so I get to keep pitchers for a year or two. The worst is N.flava.. I still haven't figured out its deal. Maybe it's the humidity thing. It's grown 2" since I got it... 4+ years ago.