Hi,
The matstats are simply a low wattage on/ off stat that they can sell for a reasonable price.
As long as it is on a stat I don't forsee any problems with putting a sheet of glass over it (leave a small gap between it though not a tight sandwitch job ).
I would recommend drilling out a few holes for air circulation when you drill the hole for the wire and then using spacers to keep the glass from sealing them.
A bead of silicon round the edges should prevent any snake pee or spilled waterbowls from causing any problems and still be fairly easy to remove if needed.
dr del