I took my big Explore bag to the Alps last week. It coped nicely with all the clothes & ski gear needed for both me and my boy (Joe, 13).
But when I got back to St-no-bloody-luggage-trolleys-Pancras and had to carry it the whole length of the Eurostar platform (394 m /431 yds according to wikipedia), plus the customs hall and half the terminal, to the taxi rank... I nearly earned the heart attack & pulled muscles that I'd managed to avoid for 7 days on the ski slopes!
Note to Explore's Branded Goods Manager: order bags with wheels next time!