Like others have said if you get an Ag spec telehandler it will outwork your 4020 and not even know it did something. We used to have a 2wd tractor with a loader and still have it as a backup, but when the telehandler goes down, everything around here stops. It will be the last piece of equipment to leave this farm after its loaded everything that doesnt have its own power. 

we have a 7-23T gehl which was built buy manitou, 7k lb lift and 23 ft max height, we have a 2.75yd bucket on it and it will fill it digging virgin yellow clay. The way the weight is distributed its pretty equal so they get around amazingly. Weve only been stuck doing things you shouldnt be doing in the first place, and thats very very rare. 

Ours has the 4 speed with the torque converter, sometimes I wish it had a hydro for doing fine work or just inching, you have to really stand on the breaks, but thats where the boom out/in comes in real handy, just get close and use the boom for fine tuning, but I know the hydro ones arent as good at digging dirt either.  New ones have a CVT which would be the best of both worlds I think.

If youre going for an older one with an enclosed cab make sure you get A/C the first one we looked at didnt and we didnt think itd be a big deal, but it gets hot in there quick even with the top door open and the back window open. And theres lots of times when loading ground hay or scooping dirt that you get so much dust its not even funny. Glad we got one with A/C

Hydraulic bucket attach is really nice, we switch buckets, and forks all the time, sometimes multiple times in an hour.