According to WadeF and others, TEN minutes is the limit for a full power LED drop-in for the G2 with the Nitrolon head. After that the module will start to hurt itself from the heat generated. Some modules may show a decrease in output as the damage is occurring.
If you're good about not leaving it on continuously, or if you're an Alaskan dog sledder (or have other forms of active cooling) then you should be fine. That drop-in from Lighthound draws even more current than the ones from DX so I would expect even more heat.
There are so many threads on this subject . . . I like the G2 also but I'm done trying to put the 10 pounds of @#$# in this 5 pound light.
You can still get that deal from Cabelas where you get a 1/2 way decent 6P clone that is made of metal and can host any P60 drop-in, AND a knife, all for $25 shipped.