I think that lowii's reputation, along with that of N. rajah, is a bit unfair. Whilst it is slower than many species, it is not all that slow when grown in ideal conditions. Further, the larger it gets the faster it grows.
Lowii from Trus Madi gets extremely large. The variants from Mulu and Murud are considerably smaller. The Kinabalu for is somewhere in between. Those are the main varieties in cultivation, but lowii, like ephippiata, has a much broader geographical distribution than previously realised.
Anyway, it would be good in a terrarium for several years. Once it matures though, it would need a greenhouse or much larger set-up.
Cheers, Hamish