I think that the quality of the Vodavi product are very good compared to the price.
For users and customers outside the USA, Vodavi is known as LG.
To translate the Vodavi product names to LG product names, I have prepared this list:
Vodavi XTS = LG LDK-50/100/300/600 series.
Vodavi Telenium = LG LIK-100/300 series.
Vodavi Triad = LG GDK-series (GDK-16E, GDK-20W, GDK-FP-II, GDK-100, GDK-162 and GDK-185).
This list should make it easier to comapare the PBX'es.
Best regards from the doktor.