I used to have those tires on my rig. They will make you appreciate the difference between an aggressive M/T and any sort of A/T tire. If you ever find yourself losing traction, just turn your steering wheel side-to-side slowly while accelerating slightly and those awesome sidewall lugs (got I miss looking at those

) will find something to grab onto, especially in mud and on hill-climbs.
Don't worry about highway driving. I had the same size on my stock wheels, and they felt fine on the highway where I tend to cruise at 80 MPH. Mine only last 28K though...but I was extremely rough on them. My only real trail run with my local LOST chapter took a few lugs from two of the Destinations, so I will tell you to be cautious with the skinny petal around rocks. And don't forget to air them down on the trail, it makes a HUGE difference. I'd recommend 18-20 psi on the trail and 33-35 on street, least that's what I did. Like I said, the only reason mine didn't last that long is because of how rough I was on them and how bad my alignment was for a good 3 months. The missing lugs also threw the tires out of balance.
I'm sure you'll love them. I hated the noise and wet pavement handling, but it's worth it for their offroad abilities. I particularily found joy in their ability to plow through deep snow on the roads. Last winter, when we got hit with a few good blizzards...I didn't have to go but down my driveway to find the fun!
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2003 Limited, Silver - L.O.S.T. # 068957 Rockies
http://www.cardomain.com/ride/2127390/14
2006 Kawasaki KLR650