Captain sensible(intoxicated) here uses woodchips AND vermiculite. I've got woodchips for the main part of the viv, but their hides have vermiculite in.
The only reason for this is because i saw how much Kelloggs liked it when my others were nesting.
I still have my old nest boxes in as hides because they like it in there so much, so they get nice new vermi in there every week or so. Oddly enough since i've had vermi in the hides, they're never poo'd in it, but beforehand poo in the hides did happen every so often. Wonder if there's a reason for it.