I recently got a epiphyllum oxypetalum cutting piece, I currently have it in a glass of water with the roots starting and will need to put it in a pot with soil soon.
I would like some opinions on what soil would be best. It sounds like cacti soil mix would work, but I am also wondering if normal peat based potting soil mix would work or if it would be too damp?
How particular is it to soil type?

PlantMatt, When we started with eppies we started them in a mixture of sand and soil, some in just sand and some in just a good mixture of soil. But in the long run we have switched them all to a good mix of soil. Neglect is the key, don't over water and shade. We only fertilize them once a season.

E.Oxpetalum is an easy Epi to grow, however for all Epis you need a free draining mix to grow it in.
A cactus mix is ideal. Normal potting mix is asking for root rot.
A low nitrogen slow release fertiliser is optimal.

I use miraclegro 0.75 cb-ft though it is for in ground use. I don't have any problem with my epi plants. The soil is on sale at lowes and homdepot now.