The loader on the Kioti DK series (KL401) lifts about 300 hundred more pounds than the Kubota LA8xx series loaders, but the Kubota loaders have about 500 lbs more curl/breakout strength (measurements at the pins) ... overall their designs are very similar (cylinder size, hyd. pressure, hyd flow, basic geometry, etc.), so it's not rocket science to figure their capabilities are generally comparable.
I have lifted and carried a big round bale with my Kubota loader, but it wasn't fun and I wouldn't recommend either of these tractors (or similar models of other makes) for such chores on any kind of regular basis. The issue is not loader strength, it's tractor stability. We had a 2,000+ lb backhoe on the tractor, so the back end was firmly planted, but there were plenty of warnings that sideways stability was not something to be taken for granted. The "compact" footprint of these tractors leaves no margin for safety, so any uneven terrain, potholes, slightly low tire pressure, soft ground, unbalanced loading of a bale, careless operation, or whatever, can put the situation out of control. For routine, safe large bale handling, you want a bigger tractor.
I have lifted and carried a big round bale with my Kubota loader, but it wasn't fun and I wouldn't recommend either of these tractors (or similar models of other makes) for such chores on any kind of regular basis. The issue is not loader strength, it's tractor stability. We had a 2,000+ lb backhoe on the tractor, so the back end was firmly planted, but there were plenty of warnings that sideways stability was not something to be taken for granted. The "compact" footprint of these tractors leaves no margin for safety, so any uneven terrain, potholes, slightly low tire pressure, soft ground, unbalanced loading of a bale, careless operation, or whatever, can put the situation out of control. For routine, safe large bale handling, you want a bigger tractor.