I opted not to get dual panes. There is no financial incentive to conserve heat/AC like in a stix & Brix because electric generally included in site fee.
Many proclaim how the dual panes block sound and the interior is much quieter, which maybe true however I have yet to have any noise issues. I'm not looking for absolute peace and quiet while camping. I can't justify the cost of the upgrade just based on sound reduction.
Lastly and maybe most importantly I am a weekend warrior and just don't camp enough to warrant the cost of dual panes, especially when there is no savings for reduced energy use.
I don't think the weight of the windows themselves is a factor at all. The additional weight is neglgible will not matter one way or another.