I have had the Sporttube 2 for 5 years now and although bulky does a good job at protecting the ski's and I am able to get many of my extra clothes in there too. I am very happy with it
Also have used a double Sport Tube for 6+ years. It's been handled by Ship Skis (Fed Ex) twice, and by the airlines the rest. The case has scrapes, scratches and dings, but the contents have always been undamaged. With the the two packing tubes, my gf and I can put enough clothing, gloves, etc. in the tube that our suitcases are 7-8 lbs. under the weight limit, even for a two week trip.
That said, it's a royal pain to load. Skis have to be aligned just so, poles just barely fit and several nylon straps and ski ties are needed. Then, the whole assembly has to be slid into the tube. Pretty much a two person task, and a real relationship tester. For me, the benefits outweigh the disadvantages.