Looking at the two, the big differences I see aside from the price is that the Herpstat has multiple temperature probes while the VE does not or at least it appears that it doesn't, Are there any other major differences between the two? I'm adding a 2nd rack and a 3rd rack in the summer. All racks are housing hognoses and sand boas with the 3rd housing baby hognoses. The sticker price on the Herpstat 4 is tough to swallow but I'm not about to skimp on a thermostat or cut corners.
edit: I'm using V-18 racks and a colubrid rack from C-Serpents.