If I understand the IVT right, and I think I do, there should be one single speed where the transmission is running nearly 100% mechanical. The hydrostat portion should be stopped and just in the holding mode. At this specific speed, and I don't know what that speed is, the transmission should be as efficient, or nearly so, as a mechanical transmission. The further away from this speed you get the hydrostat progressively becomes a greater portion of the transmission output and therefore will become less efficient under a heavy load just as a hydrostat would be. I think I understand it right. If not someone can correct me.

So..... if you can find out what this speed is, and that speed fits most of your heavy tillage or at least pretty closely, the IVT still could be pretty efficient under heavy tillage and still have the advantages of variable speed for utility operations. If you are doing heavy pulling quite a ways from this optimum speed, the inefficiency and high fuel use will show up.

John