The cooktop/vent are located on an island in the kitchen. The duct runs under the slab (6" PVC) outside it turns vertically to about 18" above grade and is protected by a rain cap - this is all to code and is not what the inspector is finding fault with.
His specific statement was that the vent was not to be used with an open flame gas cooktop per the manufacturer's installation manual.
I suspect he may have grabbed the manual from the original vent (which was a cheap model). The previous homeowner left all the manuals in a kitchen drawer so it is a possibility.
I have contacted GE directly and they told me they will do a little research and give me a definitive answer shortly - I wanted to do this to be sure before I confronted the inspector again...I'm a mechanical engineer, and as you may know, we're a pretty anal bunch. Funny thing, my company holds a mechanical contractor's license in the State of Florida.
Vent Installer's Manual:
http://products.geappliances.com/Ma...RequestType=PDF&Name=49-80777-1_HIRESr1s0.pdf
See pages 9 & 12 where installing the vent with the Monogram cooktop is specifically addressed.