I just had to tell someone. I've been searching for a carry on bag that can hold a rig and finally someone has come up with a brilliant one, the IT-0-2 by Landor & Hawa.
This one is ingenious as the handles are down the side, not the middle, so a flat base to pack in and comes in a good size 55 x 38.
Just flown out to Florida with a Javelin/ Sabre 150 rig and an Apple mac - all in hand luggage allowance, now up to 23kg with BA.
here's an example
http://www.directluggage.co.uk/it-0-2-super-lightweight-two-wheel-cabin-trolley-case-55cm-black.html
Not linked at all with the company, just one very happy customer, hope it's useful