The second statement (concerning warranty claims) was speculation on the racers' part (cooberated by several dealers at the time). The light boats were made for a only short period of time before the weights started up. I was the NAHCA secretary in the meetings where the 16 weights were a very hot topic between the class and the manufacturer.('89 Chicago, '90 Myrtle Beach and '91 San Diego). The reason behind the change is really moot at this point. The boat weights varied over time and that's that.
I bought an '84 red glue seam boat in 1983 that weighed 312 lbs. It had factory installed lead shot in the rear pylons to bring it up to 320. A rear pylon shoe came loose in the hull (about 1988). The starboard front pylon shoe split (with a loud bang) at the '93 Nationals in Wildwood. Both were repaired and the boat continued to be a highly competitive boat even after I sold it in 1997. It's still being raced, albeit only on Sundays at a small lake in Pontiac, MI.
I also owned a 1989 Nationals boat that weighed 345 lbs. It was a complete pig - the slowest 16 I've ever owned.
I now have a '98 that weighs 321 and is probably the fastest 16 I've owned. My biggest problem now is finding a minimum weight crew thats over the age of 10.