My estimation of Clutch is continuing to grow. Earth Rocker is a great album, and I do like Robot Hive/Exodus. I prefer their hard rock style to the jam band thing, and the second half of Robot Hive goes very jammy and starts to lose my interest. Earth Rocker focuses more on blues based hard rock. Blast Tyrant is still the pinnacle, an album that just fires on all cylinders, but I've added Pure Rock Fury to the collection, and it is PURE ROCK AWESOME. Fantastic album, close second to BT.
I'm also going to see them on December 29 at Starland Ballroom in NJ. Pretty effin' stoked about that.
I think you're mistaking the cover songs as "jammy". They're about as far from a jam band as one could get, imo. To even slightly liken them to Phish or similar crap is, well, sad.
As for the show, be sure to let us know your impressions. When John-Paul Gaster starts getting into it, he literally can't sit still and it's awesome.