A while back I was having a conversation with someone via private messanging and decided to go ahead and post the gist of that conversation here, with some minor experiment and observation.
I had done a lot of reading about Nepenthes cuttings recently, and decided to try a little experiment. I received a cutting of N. ventricosa from ilbasso and decided to cut it up a little more and root in water. I had three total, one with the top growth point and two mid sections (of approximate equal size). The two middle sections went into water. The difference in the two cuttings was how the bottom of each section was prepared prior to being submerged in water.
Some of you may have read here or elsewhere about cutting up into the stem/vine. The thinking behind this is, I've learned, to expose more tissue and surface area to promote more root growth.
On one cutting I made two vertical slits up the stem (see next picture) while on the other cutting I just left as a straight cut through the stem. I made the cuts around 6/7/08 and both cuttings currently have two activated nodes.
About a month later there is already a noticeable difference between promoted root growth on both cuttings. The straight cut has no noticeable root growth while the crossed vertical cuts have obvious root growth.
Vertical cross cuts:
You may see a little point on the first picture that could be mistaken for a root. It is not a root; but rather, where I sliced through a leaf attachment. I've read and heard of others doing other types of vertical cuts in including multiple parallel cuts and as many vertical cuts as possible.
Disclaimer: I'm not endorsing the water method of rooting for all types of Nepenthes, but it certainly has worked for N. ventricosa. I've read and heard about mixed results with other species; but, I just wanted to show one example of comparable differences in cutting methods.
It seems obvious to me that no matter how you actually root your cuttings (water, media, LFS, etc.) exposing more tissue will only be of benefit to promoting substantial root growth.
There are plenty of other examples floating around out there and I encourage you to find other, more experienced cutters "testimonials."