When I bought my BAS harnesses, I specifically ordered the ones in which the shoulder straps stay hooked to the buckles, which BAS calls "standard buckles". I felt that they would be more convenient than the ones which are separate, which BAS calls "utility buckles".
But in my recent SES experience, the airplane was equipped with the "utility buckles", and although they are a little inconvenient to buckle, they are much easier for "untethering", which is necessary in a float plane for docking and beaching. It only took me a few times to get pretty quick at buckling them. If I had to do it over again, I might very well opt for the "utility buckle" versions, considering Gary's comments. On the other hand, most of us prefer to land upright!

BAS also offers a "rotary buckle", which looks to be more convenient to put on than the "utility buckle", but at a $445 price increase--pretty hard to justify, in my book.
But whether you go for the "standard buckle" or the "utility buckle", shoulder harnesses beat plain lap belts by such a margin that there should be no discussion. They absolutely should be the first mod to a newly purchased older airplane.
Cary