I know this is an old thread but because these 3 point hoes are popular attachments, I thought I'd add my 2 cents. I've got a Ford 6600 with a Woods 1050 attached. It makes a great deal of power. It will snap three or four inch roots without drama and will dig trench or hole quickly and cleanly. It has a float feature on the boom that is SUPER handy. Allows you to scrape an area flat or put a flat bottom on a trench. The hoses are intelligently routed, the valve is modern and a two-stick type. The operator is protected from burst hoses by a shroud that covers all of them. Mine has the PTO pump which works very well. I run it at about 1200 RPM and it is quick enough and powerful enough for most projects. I have never run it up to 1900 RPM which is where my 6600 hits 540 on the PTO. At low RPM, it works just fine and is quiet enough that I'm relaxed.
I don't know about other tractors but my 6600 handles it well. The 6600 is an updated 5000. Heavier and more powerful. Full cab, large FEL, loaded rears. I have no complaints...the combination is powerful and when I'm done with the hoe, I can put it in the corner of the barn and not worry about yet another battery, clutch, diesel pump, tires, brakes, hydro pump, and on and on and on. It is a good solution unless you need a true backhoe or excavator. I'd like to be able to swivel the seat from hoe to tractor but, all things considered, for using a hoe once or twice a month, I can live with it. The 3 point system is mildly difficult to mount but nothing to get in a tizzy about.
The 3 point system on mine seems very solid. I'm not sure even abuse could break anything on the tractor. Maybe...but the two lift arms are 1" thick, the Saf-T-Lok system is 1.5" thick and the toplink bolt is a class 5 and 1" in diameter. Sure, I could build a home-made four-point but for my needs I won't bother. I will say that I would NOT mount such a backhoe on any tractor with an aluminum rear end assembly. I don't think I'd want a 3 point system on a "compact" tractor either. Just not enough mass there, IMO. But if you have a 50 hp and up Ford or Deere or maybe a 175 Allis or MF, I'd go for it. I also own a Kubota
L3130. It is a nice utility tractor but it does not have the beef to handle a hoe the size of a 1050. Nor would I mount any hoe on it without a subframe. My opinion only but the small backhoes suitable for that size tractor are OK for residential use but not enough machine for farm use. Just my opinion.
BTW, it will dig 10' 6" deep...more than enough for even a basement and will bury the largest cow to the legally required depth.
So, in summary, as long as you match the tractor to the size of the hoe and don't try stupid backhoe tricks or lose patience removing tree stumps, you'll be happy with a 3 point hoe. With small tractors, a subframe would be a reasonable addition and essential for any machine with aluminum parts.