I like the design of this compact 1 x 26650 driver, but as C.X. mentioned above, the lack of thermal management due to a "floating pill design" is a huge flaw in this light. Unless you can improve heat transfer away from the LEDs, you'll likely fry any driver you replace.
It's kind of an after thought, but when looking into purchasing multi-LED lights (esp. XML's) you really need to pay attention to how well the light manages heat. A better design of a triple XML is the Trustfire TR-3T6 here and reviewed here. The entire light engine screws into the head providing more efficient heat transfer away from the LEDs and driver.