Hey Guys/Gals

I've been in the market for a new hybrid/commuter type bike for the last couple of months. I plan on using the bike to commute to work (about 6 miles away) and to take it on a local trail which is mostly comprised of packed / small gravel. I like the idea of being flexible and being able to go on more rough trails which is why I was looking at dual sport bikes.

Now I have limited it down to three bikes...
The Gary Fisher Kaitai


Link to Kaitai Specs

Giant Roam 1

Link to Specs for Roam 1

and an '08 Specialized Rockhopper Disc that I found on craigslist (have never tried a 29er but hear good things).

Link to Specs of '08 Rockhopper

I've ridden both the Kaitai and the Roam and like them equally. Kind of bummed that the Kaitai no longer comes with Disc Brakes (that a big deal?) Never tried the Rockhopper but am wondering if it's a good deal compared to the other two bikes. I can pick it up for $400... The lockout on the Rockhopper apparently does not work so I might have to replace/repair that or just live with it. I was thinking I might put some slicks on the hopper or have a spare wheel set to make it a commuter/mountain bike...

I do have a budget and would like to stay under $650... I can get the '11 kaitai for $550, '11 Roam 1 for $609 and I worked out a deal for the Rockhopper and can get that for $400 like I said...

Overall value, which would you say is the best bet? I've been struggling over this and any advice/input is appreciated!

Thanks!