yes yes, buy all three without hesitation! the first two are essential if you like that rocksteady and that skinhead/early reggae sound. only one or two misses on each disc, in my estimation. the third volume is a bit less focused cuz it's over a longer period of time, but features some big tunes from some big players. you'll want all three.
i wonder who's pressing these though? i thought they were all run through?