I have a Millennium. My setup is similar to Bigslam's setup minus the Molle pack. I have some straps on it. THey dig into my shoulders. I don't care. I only pack it 1/2 mile each way on the longest setups. In a larger tree the chain mount can be a bit of a pain to reach around and get it secured. Takes a little practice to get smooth. Once setup, man is it nice. The Millennium does seem a bit heavy but maybe the newer models are lighter. Might just seem heavier because the platform is long. Awkward might be a better word than heavy. I think it is under 20lbs. Somewhere in the 14-18lb range.
I think ideally, a guy would have set up the chain brackets pre-season. This way you just hang your sticks, climb, pull up the stand, place in receiver, and mount the lower strap. Last week I went 100% mobile. Slid in. Scouted for the best tree. Hung it blind. That wasn't my best idea. Having the bracket hung already would have saved me much effort. Prior to next season I will have a bracket in the tree already.
Never hunted in LW, Muddy, or Leverage for mobile set ups.