I'm sorry to throw you off, but do you have any more pictures of this clump? That is amazing!
I don't have much advice for repotting, but before a month ago, I had literally never repotted a nep, let alone my entire Sarr collection. I left all my pots growing in their stock pots and it was apparent that the plants needed new pots when they started drying out a lot faster than normal.
I just took my time, and asked some of my friend that grow, and it's pretty much like repotting any other plant. I soaked each plant in a bowl of water to loosen the old soil away. Some people like to add superthrive to the water to lessen the stress. I didn't experience any stalling like I was afraid of and I had a good first repotting experience. Nepenthes roots are brittle, but the plants are far from.