After so long, I manage to compile a photo of the progress.
3 plants clockwise from 10 o'clock position, no feeding, frozen bloodworm feeding, and mineral salt fertilizing into pitcher.
In short,
- Leaf and pitcher colour is paler without feeding/fertilizing.
- Fed/fertilized plant looks healthier overall.
- Not much different in bloodworm feeding compared to fertilizing.
- Fertilizing results in more compact growth.