Dr. Hartman,
I go with the Food IgG test from Great Plains which is a total IgG test. It has worked out well clinically in my practice.
There are a number of resources, and Dr. Bill Shaw has written a number of articles on this topic, with references. Their resource section under articles is a good place to look.
Here is a link to an article on the topic of Food IgG, including Total IgG versus IgG4, which part of the lecture slides where built from – http://www.greatplainslaboratory.com/home/eng/ClinicalUsefulnessOfTheIgGFoodAllergyTest.asp.
I hope this helps,
Dr. Woeller