Jeff
My experience with Flow Scans is from work. I installed 3 units on our Cat 3208 fire pumps several years ago. The Cats are in hot standby with a jacket water heater that keeps the block at 165 degrees. If we loose fire main pressure they start and are at full load within a second.
That might sound like tuff duty for a diesel but they've been run like that once or twice a week for the past 15 years without a hitch.
The Cat run at 2800 RPM and burn 8 GPH at full rack.
I've never been able to talk myself into putting one on the boat. I run my engine were she sounds the happiest. If I had a Flow Scan and could see that adjusting the trim or RPM would better my economy 5%, that would only save me 2 1/2 gallons over the course of a long day offshore. Even at $2.00 a gallon, I would have to run $10,000 worth of diesel through my engine to save the $500 cost of a Flow Scan.
Mike