I mean, if the notion of sub cable quality is EVER a factor, how can you in good conscience rely upon a wireless solution? Personally, I'm going to let that particular technology mature a bit before I jump in.
Copper is king.
I dunno, Tom. There's some excellent sounding wireless mic systems out there and they're carrying more of a full-range signal. I think if it's well designed, optimized for those few lower octaves and combined with our reduced-sensitivity to distortion in those lower octaves, I don't think you'd be able to tell the difference.
Of course, you'd have to worry about your neighbors breaking into your wireless sub network and stealing LFE.