I've discovered an excellent soil mix is 2/3 long-fiber sphagnum (LFS) and 1/3 peat; I wet it and mix it, and then run it through an old food processor. A fair amount of water is added so it will process, and I use rainwater (<10 ppm TDS).
I then take a large handful of pine straw, and cut it by hand into small segments (3-4 mm). I mix the whole mass together, and then wring the water out of it, a handful at a time, over a colander. Breaking up the clumps, what results is light and spongey, and very consistent. This process also has the benefit of washing much of the mineral content out of the soil ingredients. I fill a 10x20 garden flat with 3"x3" suare pots, fill these with my potting mix, and wet them down thoroughly until they are drenched and compacted down naturally. Finally, I seed these with a few strands of live sphagnum moss, and leave them outside to be rained on and have further minerals leached out.
Once the sphagnum covers the surface, i transplant my plants from their old pots (typically heavily infested with slime mold, algae and non-sphagnum moss) into these pots.
All plants thus transplanted have pretty much exploded with new growth.
For smaller plants, I skip the live sphagnum.
This is very labor-intensive, but I am ending up with MUCH healthier plants.
For plants that require a very open, porous mix, I cut this medium with 1/3 to 1/2 perlite, or if I am filling a pot bigger than 5"x5".
The old potting medium had compacted down so much, I am amazed the roots didn't just all rot away.
This new medium has worked very well with all my CPS, mexi-pings, temperate pings, utrics, VFTs, Drosera, and Neps.
The small amount of pine straw really does seem to make a difference in the unofficial comparison I've done. It stands to reason, as many temperate CPs thrive in pine barrens, where the pine straw acidifies the soil.