What are the advantages over a SSTC?
Bigger sparks for the same power input. Theoretically, an advanced pulsed SSTC could equal it, but this has not been done yet. (EDIT: The DRSSTC by Jimmy Hynes achieved 66″ sparks with about 1.1kW input: this is better than any OLTC to date. See it here.) No gate drive transformers to worry about.