Well I haven't personally used it and I usually recommend it, but I heard it was changed (yes last year - still, knowing how long oxbow has been around, it is a recent change of formula. It was not changed before, from what I know of all the years it has been on store shelves.).
I just have heard/read some things said about it on other forums by some people who switched to it or were using it with the old formula and noticed changes after the formula was changed.
I don't know how true it is, I don't use it. If you do a search on other chinchilla forums, perhaps you can find where those people who have been using it, spoke about it. I don't want to say it, since it is not my personal experience with the diet and I don't feel it would be appropriate for me to just repeat what was said.