Well I have no way of telling if the driver heats up faster or slower than the diode but the run time is about a minute and a half. It takes about that long to start dropping in power on the LPM, I have run it over 2 minutes but it got very warm then so I think about a minute and a half should be the limit. Its a new PLTB450B 450nm I put together on Aug 3rd (build thread coming soon) have run it some every day, it measures 1913.6mW on the LPM. Here is a photo of the driver:
The host is not a common one and is larger than a C6 so the run time is good, here is a photo of the host next to a C6:
I will post a build thread on this thing soon, I took too many photos.
Really I am sure you don't have to worry about the X-Drive except at higher powers.