I think Mako Spearguns sells that light with their logo on it, so you could search for reviews of that too.
Wow thanks! That was really useful --> there seem to be pretty good reviews on the Mako Spearguns version. Although strangely their website only lists CR123 batteries and not 18650. I think I might just pick one up from Taobao.com and see how it goes!
For the reference of others who may be interested in the torch:
Mako Spearguns page: 680 Lumen Dive Light | MAKO Spearguns
Youtube video:MAKO 680 lumen gun light mount - YouTube
And some first impressions: opinions on the mako dive light...real world/ hands on-- if possible!! - Spearboard.com - The World's Largest Spearfishing Diving Boating Social Media Forum