Trek 4900 vs. Cannondale F300 vs. Spez Hardrock Pro Disk

I'm a roadie looking to to ride at night without trashing my expensive
skinny tires in the dark; a little off road riding as well (can't say
mountain biking honestly--I'm down in Houston). I'm 6'4" and ride a 63 cm.
road bike, so I'm figuring a 21 in mountain bike--that cuts down the field a
little. I've looked at the 3 bikes above -- anybody got any opinions about
them?

Thanks,
Kalukis

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