Any one use these bottles or the Nalgene ones. The Evernew (found them on End2End trail supply-- https://www.end2endtrailsupply.com) bottles are lighter than Gatorade bottles and I am not sure if it's good to keep refilling Gatorade bottles. Though I do switch out the Gatorade bottles when ever I have the chance. Please give me your opinion of the collapsible type bottles.