i went philippines last year and took cathay pacific. it was the first time i took that plane and the first i took my 70-200f2.8 lens which weighs near 2kg on its own.
packed it all in a lowepro fasttrack 350 backpack which i used previously before in emirates and never had a issue.
Anyways to cut a long story short, i got denied when i was trying to checkin at heathrow.
the hopeless woman kept insisting my carry on lowepro backpack must weigh no more then 5/6kg and that i had to put my dslr with the 70-200 attacked in my luggage(****ing no chance) or my laptop(sorry, again, go to hell) and after arguing and pissing around for nearly an hour, went away for a couple of minutes and approached and checked in my stuff in another desk!
went through easily. no issues. no questions asked.
When i was going back home from philippines they this time weighed my gear and after the knew it was because i had pro camera gear and laptop they was fine for me to go through after a quick chat with one of there line managers.
This is why when i go florida in two months time i dont think i will bring my laptop. This is why a device like a nexus 7(finally getting back on topic lol) looks ideal IF i can connect my dslr or card reader and upload raw files on it and then sync and back them to my dropbox so later when i get back home i can PP and upload them.
edit: i also carry on a couple of medical supplies like my inhalers and a couple of snacks as well(crisps, popcorn etc) but that doesnt weigh too much