This statement will put you at odds with a lot of A60 followers 
Osram GD is not bad at all, I especially love the tiny die. But how do you handle the extra heat? Even Osram GD at 350mA will accumulate heat within a few minutes.
Stock driver, as with any other ultra-cheap driver, will be a lottery. Some will handle 4.2V, some will not. But it is entirely possible you lose your boost circuit, then it becomes a 10440-only light.
I like my MRV very much. Have measured(!) throw over 400 meters. You really cant expect much more.
I removed the stock led from the board and mounted the Osram on it with a large amount of Fujik.
This may do for the moment.
I have a Trustfire F20 with a Q5 in the pipeline from HK. I plan to swap the Q5 with an XML, and use
the Q5 in the above light. I may change the driver to a 1.5 amps I have. I have a friend which can use
a lathe and may ask him to make me a metalpill for that combo.