The US Rangers have already done this. The Humvee was too big, cumbersome and slow for special forces missions so they bought Land Rover Defenders for the role, very similar to the legendary 'pink panthers' used for decades by the SAS.
http://commons.wikimedia.org/wiki/Image:US_Rangers_Land_Rover_Defender.jpg
You don't say.
Gee, I wonder what the GMV program was all about.
The faults with the HMMWV are: small internal relative to external volume; poor fit in the CH-47 and MH-47; undeniable US- and client-only vehicle. That, and two different complete sets of drivetrain parts, down to the rims and tires, which guarantee you to have the wrong parts at any given time.
The vehicle you link replaced not HMMWVs but a mixed bag of armed and roll-caged M151s, Toyota HiLux pickups, and Chenoweth sand rails, that were intended for mostly on-pavement activity such as airfield seizures.
d.o.l.
Criminal Number 18F