Wow lot's of views on this one! I'll wade in with my own experiences. I would not use the FEL for anything serious without a ballast box or a reasonable size implement on the back. My tractors with FEL's also have loaded tires. My most recent tractor was a L3901, shortly after delivery I tried to lift 2 metal mesh cages (maybe a total of 400lbs) without a ballast box or significant attachment, that was enough to lift the back wheels and made me realize that my dealer forgot to load the rear tires. It's very easy to have issues as the FEL is carrying the weight very far out in front from the pivot point. You will feel a lot safer with a ballast box.
Remember there are many other factors about safety with FEL: carry the weight low when traveling, avoid sudden manovers, drive slowly, find level ground etc, I've give this lesson so many times to my teenager who is operating under my supervision, I just hope some of it sticks.
Good luck with your new tractor