All my hamster are in similar style cages to the zoozone and not had any chewing at all so I think there are a few that will chew there way out but this does not apply to all gerbils/hamsters so there for you can't really tell someone that because its a gerbil it will defiantly chew the cage as my 2 have not.
The reason I moved them from the glass tank to the zoozone is because a) the zoozone is much lighter easier to move around where as the glass tank is heavy and awkward b) it much bigger plenty of room for 2 and c) I have not been able to find any larger tanks for a good price, they are expensive.
If I lived in a bigger place and had the room I would consider the ikea detolf but as i have limited space and need to be able to move the cages myself the ZZ2 was the best choice for me
As for having the bedding coming over the base i don't find this an issue as i just take the grill off the top and use a dust pan to scoop out the dirty bedding then top it up with fresh bedding I rarely do a full clean out.