KK,
Here is the message posted by dnewma04 at PE.
"I recently built a 7.7 cubic foot box (tuned to 20 hz) with a Dayton DVC 15. Due to amplifier constraints (only stable into 8 ohms) I am forced to just use one coil and short the other. The amp is a 300 watt mono amplifier. Is there any possibility that running only one VC will void the warranty?
Dave"
And the response by one of the techies....
"Dave ... the driver will still be under warranty.
-Paul"
I also asked my brother, who is more knowledgeable than I who quickly said, "What a waste, but you won't damage anything."
So, either the JL Audio techie doesn't know his speaker fundementals, or he just has to stand by the company's policy.