I have just started using Oxbow for two of my gerbils. They have their top teeth missing so need to eat soaked food. I figured giving them all in one food would be healthier for them and they do really enjoy it. They have looked extra shiny and healthy since they've been eating it too.
I recently bought a bag of Oxbow myself and mix in a little bit of Oxbow with the Ecotrition. It took them all a bit to get used to it, but so far all four of my gerbils love it! Of course it's not the delicious stuff so they tend to eat it later on when all the corn and seeds are gone. xD
I picked it up because I've been using the Oxbow hay and always seemed to do well.
Personally I don't like it as the sole food in the diet. Gerbils need more grain variety and animal protein. They are not herbivores like the other animals oxbow makes food for. They are omnivores who eat insects and any small protein sources they can get. They will happily eat chicken and would eat baby birds in the wild if they found some. Watch them tear up crickets and you'll never doubt their carnivorous side. I would only feed oxbow's food if I was feeding insects or poultry meat and adding a few grains from the bulk bins at the grocery store or feed store.