Adrenalin's are NOT in the "extreme lightweight" category, and they don't look like they'll hike very well, sole doesn't look like it has much rocker.
Look at the Scarpa Spirit 3/4, or a Garmont Mega Ride. I don't have figures in front of me, but the Spirit 4 should be somewhat heavier, but significantly stiffer than the Mega Ride. From what I hear, the Spirit 4 is stiffer than the old Denali TT, which was always considered the downhill-optimised boot in the lineup.
The Matrix is just adequate for me, for downhilling but I am somewhat of a lightweight, so you might want to go stiffer than that, but I'm skeptical of this whole new category of crossover, replaceable-sole AT/alpine boots. They look too stiff/heavy.
Flex comparison:
http://www.tetongravity.com/forums/showthread.php?t=78437