The first question to ask is what are you trying to do with the stormwater, treat for TSS, trash, TPH, etc. If you review the different postings there are some good references for the different products. First understand the regulatory requirement, then start the equipment selection process.
If you look for the following program, you will find papers on both Stormceptor and Vortechnics.
· Technology Assessment Report prepared for The Massachusetts Strategic Envirotechnology Partnership (STEP)