The 'planes are so much bigger, so more luggage can be carried, I expect.
I'm re-posting this, as it contains all the information I have on surviving with a very small hand luggage allowance:
My cameras and lenses have separate lightweight bags which I have managed to fit into a very light North Face rucksack for airline travel. The "Flyweight" range also include a larger rucksack and a duffle bag, but I chose the smallest, which weighs 10 ounces:
I intend to carry a stronger bag, stored in my checked luggage, which is heavier and also safe for use in city walks. There are also fabulous strong polynylon.sacks which protect from moisture. Combined with bubble wrap, these should make shock-proof and very lightweight systems for putting into rucksacks:
I find the staff in the Snow and Rock shop in the Dundrum Centre extremely friendly and helpful. Rather than buy online I have been able to see anything I need before buying: