Elmarachi Jim goto Grapeaperacing.com and read their theories on connecting rods. I do agree with them. A also said that alot of this has to do with application. The other issue is that the exhaust stroke is the hardest cycle on the connecting rod. No loads. Weight of "H" or "I" rods can be the same. I like the fact of spreading out the load on an "h" rod over a "I" rod. Most rods with "I" design have a narrowed out center to save weight. So to some degree they are an "H" rod. They are just not grooved out of the centers. Like I have been looking at GPR rods of aluminum for next motor. with proper setup and warmups, see no problem with these rods working for years and weight about 110grams less than BBC rods. This also means dropping weight in the crank shaft. Need more clearance for rod to grow in motor of about .005-.008" depending on rpm. Other side note, there is a big different between a diesel motor bottom end and a gas motor. Just compression alone and the extra amount of hours or miles a diesel runs more than a gas motor. Oiling system is different also. Can't compare apples to bananas.
Rick L.