They are a great stock option.
However they are rather heavy and will turn your M1A into a chassis style gun that you will need to shoot off a bipod / rest / ground.
(so easy positional shooting pretty much goes out the window).
One note is that there are 2 different gas block sizes when you are ordering it, so make sure you get the right one for the model of M1A that you have.
Putting them on is pretty easy.