I'm one of the (un)lucky recipients of a WW with a "not so flat" base. Using a straight-edge and a feeler gage, I determined that mine is concave by 0.003" in the center. This is horrible to be called a 'lapped' finish. Most of the time when you you buy barstock the dimensions are guaranteed to +/-0.003", so DTek's really not improving the finish at all.
As expected, the performance is dismal with this base finish. After 3 installations, I never saw temps better than 43C idle. I have no doubt that this block would perform ok if properly lapped, but right now it's performing worse than an AX-7 heatsink.
I understand that these are based on Cathar's original design, but it's obvious they're not made to the same standards. I think it's a little bit of false advertising for them to be linking to BillA's review @ overclockers.com, inferring that DTek's aluminum and poly topped whitewaters perform the same as Cathar's Australian made, copper topped whitewaters.
When any manufacturer moves their manufacturing facilities, or re-tools an existing facility, special care must be taken to make sure that the product meets the same standards (AKA performs the same) before and after. I fear the proper precautions have not been taken in this case.