How robust is the Thorfire S70 driver?

I have an extra S70 still in the box and thought I might try my luck with a multiple XHP50/70 configuration. Just curious if anyone has really taxed out the stock driver, perhaps using the ‘solder blob’ mod and multiple emitters. My other S70 is spring bypassed with the solder blob and it runs just fine, but that’s with only one led too.