The Kubota loader pretty much matches your tractor for capabilities. Any FEL is a compromise in weight, force and payload. We like to think that Kubota took it all into consideration in their loader specification.
Key things to consider -
1. Weight and CG of the empty loader/bucket. Generally, the CG is out in front of the tractor, so the weight effectively doubles on the front axle/tires. It also lifts the rear end by probably about half its weight.
2. Your payload CG is farther out in front of the tractor, so the same applies, only worse. The payload weight again is effectively doubled on the front axle/tires, but picks up the rear end by more like 75-80% of its weight.
3. The strength of the loader itself has to be matched to the tractor - you certainly don't want the loader to crumple the first time you hit a boulder.
Most of the members here recommend you have about a thousand pounds of rear ballast for loader work. I have filled rear tires - about 250 lbs/tire, plus 140 lb weights per tire, plus a 600+ lb concrete block on the 3 ph.
Kubota says the max load for the front axle is either 2650 or 2850 lbs - I forget which. The empty loader (because of the CG), plus the normal tractor weight, pretty well has you at the limit. It also has you at the limits for AG tire load ratings, although R4s do better.
Anyway, you really wouldn't want a heavier duty loader; the tractor isn't made for it. Similarly, you wouldn't want lighter duty; the tractor can bend it up. For the fit, OEM is the way to go. Your Kubota dealer is more likely to stand behind any tractor/loader? issues if it is all Kubota.
As for price, the Kubota model appears to be in line with the name brand equipment.
