Gear, synch shuttle, power reverser, CVT, HST--tremendous variety of transmission options out there, and all with millions of hours of time that have helped refine them. Gear is the oldest technology, and most proven over time, but HST has been around for decades. In the size you're looking for, I'm pretty sure its the most popular configuration for ease of use, and the option is pricier for manufacturer and consumer. I wouldn't let one opinion make up your mind. Old mechanics can tell you better than salespeople what they've seen for transmission problems most often--abuse and lack of maintenance will probably be what they say.
Good luck shopping, and take a bunch for a test drive--hopefully the dealer will have some piles, obstacles, and field to go through the paces and see whats most comfortable. Loader work, parking lots and tight quarters, the HST is hard to beat for ease of direction change and slowing down--they slow down/stop if your foot slips or you do nothing--gear has to be disengaged and braked to stop the progress. If your work is wide open and there's no fine work areas or rapid cycling of direction changes, the gear puts the most HP to the PTO--5-15% loss to go HST. I have HST on mine and love the ease of use and precision it offers.