I believe most PSCs were fitted with these two-pin connectors. The ones PSC used were pretty high quality, either Perko or Cole Hersee. Advantages -- they are typically polarized, water-tight, and rated for fairly high amperage (10-15 amps). Disadvantages -- the obvious one already mentioned in your post, that many accessories have cigarette lighter style plugs and, second, the two prongs can sometimes a bit difficult to plug in. To deal with the first disadvantage, it's a fairly simple job to cut off the cigarette plug from your accessory and install a two-prong connector using a couple of water-proof butt connectors. Or, you can go the other way and splice a the female end of a cigarette-style plug to a two-pronged connector and make yourself an adapter.
PSC 40 -- #46