chriscanivorous wrote:Im going to use peat/perlite/broke up polystyrene(instead of silica). at a 40/30/30 medium and a layer of live sphagnum on top
If you live in a very humid environment, that mix ratio sounds OK. If you live in a less humid environment, you might consider changing the mix ratio to 50/25/25 (sphagnum-peat-moss/perlite/polystyrene-bits). The live sphagnum moss will be problematic if you use it with Venus Flytraps, because the Flytraps will like more direct sunlight and heat than living sphagnum may prefer. So the live sphagnum may be uncomfortable and the tips may brown and dry out, and if you keep the live sphagnum moss wet enough for its own comfort, you would probably be overwatering the Venus Flytrap and might encourage rot.
Live sphagnum moss works well in some conditions (cooler temperatures or with plants that like diminished light in hot temperatures) and not so well in others. This is just one grower's opinions. I'm sure you'll get other opinions to consider as well.