It is amazing how folks believe the reports from small companies about cars that run on water, spring loaded cylinders that mount in your trunk and make the car handle better, and strakes that solve all manner of handling ills. I have chuckled at the strake issue for a few decades, frankly.
I would suggest that the company that designed, tested, and certified your helo is the best source of advice. When they say things as strongly as the quote you provide, I believe it is fairly obvious that they are warning you, in no uncertain terms.