I'm not personally familiar with the product, and can only offer the casual observation that the only way to know for sure is to try it.
As someone who used to cater smallish events, which overlaps a "private chef's" duties, it might be worth your while to make a few quarts of demi-glace every so often and freeze them. Home made demi beats bases by a considerable margin. But if you don't have the time and/or space, you don't. It's not worth killing yourself over, especially if you're using the commercial demi as a sauce component in a compound sauce rather than as the sauce itself.
Finally, to resurrect an old argument, demi-glace is always made from an Espagnole. A straight reduction is just that, a straight reduction. In terms of classic sauce preparation, straight stocks are most economically and efficiently used by reducing to the glace stage, then reconstituting from there. That's the best way to manage their intensity. A demi on the other hand, has a lot going on besides "essence of meat," and too much reduction alters it. And that brings us back to the main reason that home made demis are better than commercial bases.
BDL
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Ex owner operator of Predominantly French catering, ex cook at a couple of good joints
