Bought two of those covers for my new DBR10's and I can't think of a logical reason why I shouldn't have got them.
The quality of the materials is 10/10 !!!
Once you unzip both front zippers, there is another mesh that allows to use the speaker with the cover on, and keep it dry even if it rains. At the top there is a velcro flap that covers the handle, and at the back there is a whole contraption of various other velcro flaps that will cover the speakers I/O and fan ports while keeping any water away. At the bottom there is another velcro strap that adjusts the tightness of the cover on the speaker.
There is relatively thick 'sandwich' of mushy foam between the both layers of fabric that will additionally protect the box from scratches, direct hits or occasional bumps during transportation for many years.
Can't really think of any cons about those, they are very rugged and looks like they would last very long, and definitely is a very worthy investment if you like to keep your speakers in pristine condition.