I haven't tested the Da's response yet, so I could be wrong, but I doubt the IR filter has been removed entirely.
I'm willing to bet that Canon simply enhanced the transmission thru the filter of the red end of the spectrum. Much like the Baader ACF filters do for modded camera's, which still cut above approx. 690nm, including the IR, just like the standard canon filter does.
My Baader modded 300D took great shots with custom white balance, I'm guessing it was because there is no 'extra' spectrum being recorded with the Baader, just more of what was already being recorded.
http://www.dslrastromod.co.uk/baader.../baaderacf.jpg