The SP33 has always been 3v input (single battery). The Boost driver with 6v output is a completely different driver design and would not be compatible with the SP70/TK70.

The reason they switched from the Boost driver to a 3v FET driver was because Cree came out with the 3v version of the XHP50.2. The 3v FET driver is cheaper to make and has higher output so I could see them making it. (I prefer the Boost driver version myself)

I’m not familiar with the Q8 Pro. Would it use a battery carrier to get 6v? In theory they could make the whole light 3v.