Maybe its cause I'm not old school but these are a must with heavy loads. The only time didn't prefer these was on a paddle assist frame with paddlers. I never had a problem with these moving around or slipping when I didn't want them to. A benefit of these is when it is really windy and you want to feather you can pull the rite out of the oar lock, rotate the blade 180 degrees and you now have feathering oars with handles 6 inches or so closer to each other.
bought them to use on my river boat. works great, you can worry about looking for fish and looking for Bonks, and not worry about blade angle and if you need to for finesse just pull in and turn