Soundguy, On my hydro DX33, I can put my bucket up against a large pile of dirt on hard ground and make all 4 wheels spin with the tach at 1,400 rpm. That's with loaded rear tires and a 450# BB. That is the same thing that a geared machine could do so what is the difference? If I am on concrete I can make the engine lug down also, but at some point it will hit the relief valve wich protects the clutch and drivetrain. On a geared machine, if the tires have traction and the engine lugs down, what's going to give out first? the clutch?, an axle? or maybe a driveshaft?
Having said this, I do know how to operate my machine to avoid doing these things, but I did them when I first got my machine just to find it's operating limits.