In regards to build quality - I've had conversations with people working on their boats - i.e. tearing them all of the way down to the hull and rebuilding. The following is a comment from an owner of a 1988 311 working on his boat - this is typical of what I hear when I ask others as well:
Regarding build quality, I am finding it good and bad. The hull is very solid and appears to be a minimum of ½” thick solid fiberglass below the waterline, and the sides are about 3/8” thick and have a 1/16” structural core. The original transom was two layers of 1-inch marine ply, but holes and modifications turned several segments of the transom to mush. The deck is cored with ¾” plywood sections, and there are a surprising number of small pieces between the glass. For instance in a eight foot section of the deck, they typically used four small segments. These decks are molded (gelcoat goes first, then lots of glass, lay in the plywood planks, then another layer or two of glass).
After the main deck and hull was molded, they built boxes and bins with far lower quality construction. There is plenty of resin-starved glass, where the fiberglass was insufficiently coated and adds very little strength. Measurements were eyeballed, and seldom symmetrical.
One of my biggest complaints with the build is the hull to deck joint. There is a 1” x ¾” backing firing strip that is supposed to hold the screws that go thru the hull to deck, as well as catch the rub rail screws. As built, the hull to deck joint had brass screws every thirty inches. I use this boat offshore in the Gulf of Mexico, where 3 to 5 foot waves at five to seven seconds are typical. These are not swells, but rolling, breaking, and white-capping waves that can pound your boat at speed, and make everyone wet with the spray. The first time I noticed this deficiency was sitting still in four foot waves, and water was pouring into my rear quarter at the hull to deck joint every time the waves would rise to the rub rail. My bilge pumps were working overtime that day! Brought it back to protected water and caught some bay fish, but that was not what I was after. I implemented a repair by removing the rub rail and installing a section of HDPE ½” to replace the firing strip, and sinking about a dozen screws where three had broken loose.
A year or so later, while I was about 40 miles offshore running in three foot seas, I was alarmed to see water shooting out of the inside top of my cabin. This occurred when forward screws broke loose, and wave crests had found their way between the critical hull-to-deck joint, and washed behind the cabin upholstery, run along the ceiling of the cabin and out the cabin door. This told me that the critical forward edge had busted loose and we were taking on ten to twenty gallons of water with every wave. I brought it home slow that day.
I have also heard that the Grew made Stingers (hull number starts with GR) seem to be better quality. Don't know anything about the quality throughout the years, i.e. older Stingers are better than newer ones.