The contact base for practically ALL heatsinks and water blocks are not perfectly flat. It's a part of the reason why a thermal interface material is necessary in the first place. It should be fine. I've heard nothing that suggests that there are any particular AIO or air coolers that are problematic in this way to a degree that should exclude them from consideration. Worst case scenario, even if it WAS true, lapping, just like on heatsinks, would always still be an option for those capable of doing so and doing so correctly.
I seriously doubt Corsair would continue to sell a cooling product without modifying it, if it was somehow incompatible with the most popular platform currently in use though.