If it fits, it should work. But 5A is a lot for an XM-L2. It's been done (at least on the XM-L), but you have to have really good thermal path to the water, and be very careful to make sure it doesn't run very long out of the water, at least at high. This is pretty serious overdrive, and will certainly shorten the life in the best of circumstances. I'm sure you don't care if you reduce the life from 50,000 hours to 1000 hours, but at that drive level you could easily reduce it to 1 hour, or even 1 minute. Heatsink, heatsink, heatsink.
It might be possible to reduce the current on that driver, but it would mean replacing one of the components. Not a big deal for me, maybe more so for you.
I would think you should be able to find a similar driver that's 3A or so, which would be more 'normal' for an XL-L2.
Come to think of it, I've seen your pictures, and there's no way there's good enough heatsinking in that light to run it at 5A. I wonder if maybe it was running at 3A and that shortened it's life to whatever you got. In my diving, I value high output over long life and reliability, so I'd probably go for a 3A driver. If it was the other way around, I'd probably go for around 2A. I'd only use a 5A driver if I wanted absolute max output and wouldn't mind much if it failed halfway through the first dive.
