This would certainly seem to be the ideal use case for a belt printer, but agree that you will likely spend a lot of hours up front tweaking new units to get the right. Time you would rather spend printing.
Any printer built from the ground up for performance and reliability isn’t going to be cheap. You can’t get around the fact that good design costs more than bad design (because of the skills and experience of the designer), and quality parts are more expensive than low quality parts, because quality control costs money (you have to pay for the costs of inspections, plus the amortised costs of the materials and manufacture of all the rejected parts that didn’t make the grade).
That doesn’t mean you have to sacrifice performance. While the Prusa printers are plenty reliable, based on a refined design built with good parts, it is most definitely an older design, which prints slow. Something to consider.
If I was setting up a print farm from scratch in 2022 (full disclosure, I don’t have a print farm at all), I would be looking at decent quality CoreXY machines, simply because they fit on shelves nicely, comfortably print twice as fast as Mendels for the same quality output, and ultimately time is still important in a print farm. Problem is, there is no reliable, large off-the-shelf supplier of them like Prusa. I would probably build Vorons with as good quality parts as I could buy, since the design is well tested and is solid.
Delta printers are mechanically simple, with only three moving parts that all move in the same direction, and don’t have a moving bed, which means you can make the bed thick and heavy and it will be flat, and never need levelling for the entire life of the printer (I have a Delta that doesn’t even have levelling screws, and it has never printed a bad first layer). Decent Deltas with linear rails and quality electronics are generally very reliable performers. They are fast as well. They are the sort of printers where you send the job remotely and could not even look at the printer until it is time to remove the finished part. Problem is that they are round, so there would be lots of dead space around them next to each other in a print farm, plus they are very tall, so wouldn’t stack well.