I heard both at CanJam London this year. If you just want midbass slam (which is going to be 100hz+), I remember the Cascades having the most violent kick out of everything at the show (All the Beyers, new LCD 2s, Fostex flagships, Focal flagships etc).
The Klipsch is a much better overall sounding headphone though, it's like the Fidelio X2 on crack. More bass, more highs, more clarity, more size, more everything!
I think on bass quantity alone, the Cascades will take it. But I feel like it doesn't really justify the BNIB price. Might as well get some V-Modas unless you really like the brand/style/sound sig.
But the Klipsch is on my future to get list because it's just so "kick ass turn everything the fxc up and rock out" for an open can. Price is already sub £1000 and I'm in no rush >=D
I've got the TR-X00 Purplehearts as well and honestly I just want someone to put TH-900 drivers in them one day as opposed to upgrading to a totally new can. I remember the 900s sounding superior to the 610s in every way at the show, not 2x the asking price as good - but it's more the painstaking process of building the 900s that drives the price up lol.