I grew up on a farm in West Texas back in the 50s and 60s and my Dad had no 4WD on anything other than our two cow horses. We got by but 4WD certainly would have come in handy.
I bot a 5203 and have done a lot of loader work. Have the back tires filled but think I need to add some more ballast. Looses traction before it powers down. I am tempted with the new 4WD model, but am pushing 60 and am wanting to retire early, so I need to quit spending money in such large hunks. I think I will stay with the 5203 I have (have a little 2320 also) and make it work. I figure, maybe incorrectly, that the MFWD is something else to break.
If I had it to do over again, I would strongly consider the 4WD on the 5203 or maybe even the 5303 or 5403. I think as it is, I just stay out of the mud--its the slick stuff on my hill country place that gives me fits. Guess its the same at LLano where Chip is. The deep sand in West Texas also gives me problems if I put too much of a load on the 03-- it will spin the tires until I bury up to the axle. So gotta watch that.
So...the 4WD gives you more operational options, cost more money, and is one more source of potential mechanical problems. You will run into circumstances you wish you had 4WD, no doubt. Just depends if those circumstances come along often enough to merit buying the 4WD. Its a tough decision.
I do really like the tractor, 2WD and all.
Best of luck.