A 4000SU is a few inches longer but other wise the exact same size as a 2000-3000, for those that have used them they understand their nimble compact size and how easy they are to maneuver in confined spaces such as inside my poultry barns which have limited overhead clearance of 7 ft, when using my 4000AP I have to stay bent over in the seat to keep from hitting my head on overhead equipment.
The advantage of the SU is it has the same 52 hp engine as the AP so it has plenty of pto hp to operate our decaker in the poultry barns and handles my 7 ft tiller while maneuvering in the family's multiple gardens much easier
It has the same independent pto and controls that I'm use to (no two stage clutch), also has the much better wet disc brakes that I'm use to. They have the same gearing as the AP so with the smaller 28" tires they are slower with road speeds barely making 15 mph
With it's slower speed in the hay fields hooked to the tedder I can put it in 7th gear, set the throttle at 1200 rpm and row around the field at a good pace while the tedder running at a slower speed will stir and fluff the hay without beating the leaves off, I tried this with my 4000AP and with it's larger 16.9-30's it was to fast.
The smaller 28" rear tires also means one can make tighter turns at the ends of the fields without getting the equipment into the tires.
Basically it's a over powered 3000 with the same ind pto and brakes of the larger models.
I traded a 3000 for this 4000SU, the only advantage I can give the 3000 is it's faster road speed, a SU out does a 3000 everywhere else.
How many 3000's can you hook a 10 ft brush hog to and clip pasture fields with?
As for the loader question, to only reason I would put a loader on a tractor with a sweep back axle is if it was the only tractor I had.
I don't have any "big" tractors, just an assortment of medium sized ones.
My tractor inventory
62 881 diesel, mainly a parade tractor, it was used in the hay field last year while the SU was down
72 4000SU, compact and powerful, enough said above
69 4000AP, this has been my main tractor for over 26 years, at one time it was my only tractor and did all of the work
69 4500, don't need a loader on a ag tractor if you have one of these
Old photo of when we first got it going, the yellow has faded a good bit since then
67 5000, my late brothers tractor, I've only had it for a couple of years, one of his sons is wanting it now, I don't have a problem with that.
89 6610 with cab, my primary baler tractor but is seeing more duty with the recently acquired 15 ft bat wing mower
I've recently acquired a 74 5000 that's been disassembled for 12-15 years, we'll see how that works out once I get everything home, may be fixable, may just be parts, did get a fresh 256 engine with it.