Personal experience, but mine may differ.
The only Sarracenia I've had I bought from a nursery in Utah (species unknown) and was planted in a soil/peat mix. The nursery was a very good one that specialized in succulents and tropical plants, but they admitted to this being their very first time with carnivorous plants.
Not knowing much about them myself, other than to only use distilled or rain water, I took it home and put it on an east facing windowsill. It really took off!
Within about 2 months I had to re-pot it. By this time I had gained a little more knowledge on care, but still put the entire plug of soil/peat into the new pot of long fiber sphagnum.
I even decided to fertilize it every 2 weeks with some African Violet foam fertilizer I had laying around. This plant just gobbled it up and showed its appreciation by tripling the number of pitchers, and the new ones were over twice the size.
The point is, between the nursery and me, there was a lot done that most experts will say no, no, NO! to. However, it shows that Sarracenia might be a good one to try, unless you want to clean out the terrarium and start over.
Good luck, and, if you try it, post some pics to show us your progress,
Chef