I bought my first 4wd vehicle in 2007, the 6530C, 65 hp, 4wd FEL. I downsized when I retired from 7 tractors, 2 of which were JD 4010 70 hp with FEL and 4230C. I probably have bought my last tractor but if I ever do, it will be 4wd. I didn't realize the benefit of having the front wheels helping in the pulling process but I am using the same implements with my 6530 that I used with the JDs.
With respect to FELS and tractors, 4wd tractors have much heavier front ends and at least in my case, much larger tires which are more robust for hauling loads and the larger tires don't sink as far in soft soil. My comments are based on a Ford 4 cyl 4000 and the JD 4010 my only other two FELS.