any big advantage to using adjustable rocker arms

Yep solids have to have adjustable rockers. But yes to on even HYD cams. Once you do a valve job, mill the heads etc. it is nice to be able to fine tune the push rods into the lifters. If all the machine work is done correctly however there is usally at least .050-.080 of give anyway though.

But on a stocker unless you are having issues I would not spend a bunch of $$$ on a set. No real need too.