Dont get caught up on the wattage of a LED light.
No real idea of what an Ostar will produce in the way of lumen at 15watt but my guess is it will be less than what a XML can produce at 10 watt.
In saying that I hear that Light Monkey make very good lights.
Agree. LM is top notch. My first light wat a $1000 Salvo (now LM).. It was rated at 21W and 1000 lumens... A few LEDs out there have broken the Ostar's specs now. LM are good lights but I am not sure where they are getting their Ostars because from what I now that LED is obsolete and has been for abour 3 years now!
Cree XML is the newest badass in town!
I believe LM made a 9W, 12W and 21W. I think the 21W has been down rated to 18W. I believe due to heat issues. When I got mine, it would cut off on the temperature switch. I took it in and they "tweaked" it. My guess lowered the drive current. Still a really nice light. But, it was $1000.