No need to wonder, we have data. Besides what Cree provides members such as djozz and match have generated good information.
RMM’s also been pretty specific that he gets better output despite higher vF due to the increased output from Cree’s newer stuff. The big downside of course is that with a high forward voltage CC regulation on a single sell becomes difficult. Doesn’t apply to this driver, but high current linear and buck drivers are left out in the cold.
Where did you order your SRK (kung) from? Does it include a screw-in shelf which the MCPCB sets on? If it’s a reliable source at a decent price I’m sure a few folks would be interested. It is surprising that a relatively well made light also has genuine XM-L emitters at this point.