I have come across a model data anomaly in AH, sent a very brief email questioning it. The anomaly was an error, and was fixed the next update. I have also come across primary source documentation where the data conflicted with the AH model, and found it changed in the next update.
My advise...
1. Be concious of the staffs time- Be brief with your overview of the issue.
2. Provide the primary source- (I've either sent a scan of the document page, or sent the entire document in pdf and cited the page/paragraph location of the relevent data).
In every instance where a change was made, I could explain the issue in less than 100 words. Did the research, and provided the source (as opposed to expecting them to obtain the primary source).