They're not playing Harpo's, they're coming to the I-Rock. We've played there a bunch, and that place's sound is far better than Harpo's. No giant cement pit to absorb the good sound and reverberate the MUDDY BOOM like Harpo's.
Yes, they crap all over the bands at Harpo's. Ask any band that's toured through that venue, they'll tell you it's such a crappy place to play. No back stage or dressing room, it's a precarious 2x4 staircase to the stage, and nobody cares about treating the opening acts well at all. But... Harpo's ALWAYS has the most energetic, reactive audiences, and if you want the heart of the metal scene in Detroit, that place is it.
I wish I could open up a club with a stage as large as Harpo's, but in a better location close to the freeways, with WORKING plumbing that doesn't flood every friggin night, and at least some hospitable accomodations backstage and an actual dressing room. Until that happens, the I-Rock is the best alternative.