I've already heart about a cage when degus escaped through the bottom of the cage made from plastic. But my degus aren't interested in it and it's not easy to chew it from inside - there are no corners. So I think is's quite safe.
Wires shouldn't be more than 1 cm (0,4 inches) if you plan to breed degus. If you don't plan to breed degus and your degus aren't too young, it could be about 2 cm (0,8 inch). 7 week-old-degu shouldn't escape through 2 cm wires. If the wires are horizontally and vertically too, it could be a bit more than 1 cm with babies and 2 cm with adult degus.