Don't like to jump on the wagon but, I agree with the others .It's a nice piece ,except the mounting.
It looks like you could make a hinge in place of the top bolts and then have the 2 lower holes use a pin and clip. If it was set up like that ,you could use it for every single stump and that would be a great time saver.
I know because I made one for my 252 from the existing safety hoop bar thing.It fols up out of the way when grinding and rest just before the exhaust.I made the blade from expanded metal so it wouldnt obstruct my view of the stump while cutting.I posted pics on the site a long time ago but can't remember where.
I understand not wanting to hurt the feelings of the guy that made it for you .Wait a few weeks and then just ask him if he could make it hinge so it would be even more gooder.