It is not N.'Gentle', and not pure 'Mixta', but likely a Mixta hybrid or a maxima hybrid. There's so many crosses along these lines its hard to say for sure.
I saw your thread on the Singapore BG cool house. I hope you folks can get together with them and put together a Nepenthes Garden there. From what I saw, the cool house is not very cool, and wouldn't attempt any highland Neps unless night temperatures could be lowered consistently to 10 degrees C. With all that humidity and mist, I would think lowland and intermediate species would thrive under the existing set of conditions, as well as some of the classic hybrids. Superbly grown specimens of N. merrilliana, N. northiana, N. sumatrana, N. truncata, N. bicalcarata, lowland forms of N. veitchii, not to mention the indigenous species like ampullaria, rafflesiana, gracilis, mirabilis would make a fantastic display. I hope you folks can pull it off. Good luck!
Trent