TS,
Temperature does affect pitcher size but it is only one of the factors.
It also depends on what you want to achieve.
Like I told another grower yesterday, if my Cephs at the balcony reach 2" I already consider myself a winner. That is the size most mature pitchers are at in cultivation, even overseas. But if my plants are grown in lower temperature, they might just give me 2.5"-3" pitchers. However, I am not interested in showing to the world that my Cephs have got large pitchers while they are grown in an air-con room. That is no different from setting up a highland chamber and growing N. hamata in it. Of course, N. hamata can do well inside. But what if I have N. hamata growing at my balcony?
Every grower has their own individual goal. My personal agenda for growing Cephs is to have mature plants thriving for years in true lowland conditions at my balcony, bearing well-coloured relatively large pitchers and flowering.
Insider tip: Buy Cephs with a decent rhizome of mature age. These plants give large pitchers with little effort! (Now you know why my Cephs have got large pitchers despite the heat.)