I own and shoot the 3rd generation pistols listed below. They all shoot between 1" high to 1" low at 21 to 30 feet. Most are either a tad high or right on the money, elevation-wise.
Except for the 3913TSW pre-rail that I haven't picked up yet, I've shot between 200 and 750 rounds from each of the following S&W pistols over the past two years: 669, 915, 1006, 1076, two 3913s, 3913TSW, 4006, 4013, 4014, 4506-1, 4516-1, 4516-2, 4566, 4576, 5903, 5906, 6904, and two 6906s.
FWIW, I've not found any "general tendency to shoot low" with my 3rd generation pistols. However, I will note that standard production 3rd generation pistols do not ususally have finely tuned, crisp target triggers (although some are better than others
) so it's easy to pull down and shoot low while firing them. As you can see, I shoot them a fair amount and have gotten use them.