Ran a 5' tiller on my used and abused l2850 gear drive had to monitor operating temps religiously and was slow going occasionally going over tilled area multiple times. Completely different story using same tiller with my l4150. Usually tilled after I ran a 2 bottom plow (also an interesting adventure with a smaller 2850) or subsoiler to start the process.
My L2501 HSD has no problem with the land pride RTA 1258 (forward tine rotation). Like others stated, going slow and allowing the tiller to work is key to success. I have heavy soil and have no problems. If new ground, start shallow and increase depth once the soil is broken.