The term "alcohol free fount" is a little like "100% vegetable based ink", they both are incomplete descriptions.
Founts designed to run with no IPA will often contain different alcohols, often with greatly reduced volatility, therefore by using such a fount, and continuing to add IPA to it in large %ages, you will end up with a massively aggressive fountain soution....never a good thing!!
Some founts are designed to run with "reduced" IPA, at levels of say 1-5%, thus providing the print benefits of IPA with a reduced level of VOC. Again, such a fount could have an alcohol/glycol present and the IPA level must be restricted.
Its a bit like taking painkillers...its ok to have Nurofen, Codral and Lemsip at the same time....but you must give thought to the fact that you are accumulating your dose of paracetamol, or else you will have no headache, a clear nose and soothed throat as they wheel you into the hospital
....and as for the VB, Bundy is the best alcohol!!