As a big advocate of HST, I think that a shuttle works quite well for loader use. The need to replace a clutch at 400 to 600 hours has not been my experience. I think that HST actually has advantages that far exceed even it's loader use applications. My favorite reason to have HST has got to be its ability to precisely control my ground speed while mowing. I find at my place, even with considerable work in leveling the grass areas, I still have many "pot holes" from gophers to erosion etc., using HST allows me to navigate these jarring experiences easily because it instantly slows down the tractor both because of less fluid flow and because of the resistance to movement it offers as a consequence of decreasing that flow. A manual transmission tractor (my International 454 for example) requires one to throttle back, slip the clutch, disengage the clutch and brake. The easiest is to slip the clutch to slow down unless I'm going downhill, then its clutch and brake. With HST, the speed up/slow down response is immediate as your foot decreases pedal pressure. My other reason for having chosen HST is the control I have while mowing backwards on the banks of my pond. Besides the control/auto braking on these very steep banks, it allows me instant forward/backward movement as I zig zag back and forth to position myself for the next cut. There are some areas so steep, that having the HST transmission has allowed me to cut what otherwise is a real experience with my International, a manual transmission. It can be done, but it's definitely much slower. If mowing as I describe is not part of your normal duties, you may find that the advantages of HST are not as valuable as do I.
You mention your prior experiences are running a standard gearbox tractor, I think many if not all of us can say much the same thing. It took some convincing on my part to go HST. Understand it is not our desire to increase the number of people with HST but rather simply to inform you that our experiences with HST has been positive, especially for those of us who have had, or still have a standard gearbox tractors. There is nothing wrong with a gearbox tractor and without a doubt, some situations where it is superior. Pulling ground engaging equipment like a ripper(s) is certainly a strong candidate for a standard gearbox. Rat...