I'll step out on a limb and admit that there is positively no way in (you know where) that I'd ever even consider purchasing a 2wd tractor if I needed to use it for loader work. I've been there, done that, got the T shirt, and it flat out stinks; end of story. Where I live, you'd have a better chance selling ice to an Eskimo than you'd have selling 2wd tractors with loaders on them. If you have one with a loader, I assume you can make the best of what you have, but it is so inferior to using an FEL with 4wd that it's even silly to compare. I've run teeny tiny tractors and I've run end dumps with a 15 yard bucket, and everything in between. They all basically work the same way. You can put an FEL on a 2wd tractor, but you will not be able to do anywhere near what you can do with a 4wd tractor.
It's simple physics. You take the weight off of your drive wheels and you have little to no traction. You can counter weight the heck out of the rear, but then you have a very unbalanced tractor if your bucket is empty. The worst is trying to use an FEL with a 2wd tractor on any incline. Now, that is dangerous. To simply pull, a 2wd tractor will generally do fine unless you are in sloppy conditions or you need to pull really hard. Then it becomes an issue when you are just pushing non-working front wheels through the muck as well as pulling your load. I've gotten more than my share of wheeled as well as track driven tractors stuck.
When you get into the class where you really need to pull hard in commercial applications, like pulling a pan behind a tractor, there are basically no more 2wd tractors in use anymore. They are all 4wd and now several are on tracks. I have pulled a 10 yard pan behind a Case IH STX450, which has tracks on each corner, and pulled the same pan with their older 450 hp Case tractor that has duals on each corner. On firm ground, they seem to pull about the same. On soft soil, the tracked STX pulls quite a bit harder. I also managed get a D11 so buried in the mud that you open the cab door and just walk out on the ground that is even with your door bottom. That's when you're really stuck!