I have similar setup to you Caniac Nation, as you can see in my signature. I had mine aligned and road force balanced twice because I had a slight vibration at 68-72 mph on the highway. It got much better after 2nd balance and alignment but there is still a slight vibe at the speeds i mentioned. The lift does make the vehicle operate with suspension components in more "stressful" positions but hey - for those of us without QL it's our only chance at having more ground clearance than a Honda Odyssey minivan! Anyway, I believe mine has to do with the wheels/tires - the wheel offset is much less than stock and there is also the issue of hubcentric/non-hubcentric wheels so I figured I would not have a 100% stock feel. The vibration is almost un-noticeable at this point. It sounds like you might have to have your setup looked at again because I haven't heard any of the other guys with lifts having issues at such low speeds.
On another note, after my Jeep was taken in for the rear diff. seal leak to be fixed, I've noticed a hum on the highway at 70-72 MPH only when on the throttle. It sounds like it's coming from the rear - almost like the drone of a plane flying overhead. I can't figure out if it's related to a driveline vibration, or, if it has to do with something that was tweaked when it was in for service. It reminds me of an aftermarket exhaust drone at certain RPM's I had on a truck of mine, so I don't know if it is related to them not putting the exhaust back on correctly but I doubt that's it. Do you have any issues like that?
2011 Laredo V6, OR1, RR 2.5" lift, ProComp 7036 wheels, 265/70/17 Toyo Open Country AT's - SOLD