the mrs and i just bought a cadac "easy" chef, not the smallest or lightest to pack but after testing it in the garden this weekend its a winner :-) Dare say by the time you factor in a kitchen stand, stove etc. it works out the same in terms of space / weight. The gas bottle would be needed either way... On the plus side you get a massive cooking area and good temp control, for us this & the changeable cooking plates is a winner.
If space and weight was the major factor a couple of "suitcase" single burners would do the job - they run from aerosol type gas canisters, whilst more expensive in the long run its far more compact than a stove, regulator, hose and gas bottle.
We are a family of four and we have two of the individual gas cookers that go in the suitcases. There are various makes around (ours is Sunncamp). We have camped quite a few times now and they have been brill and very fast. Our friends keep using ours despite having their own double one with gas bottle!!!! Apparently ours is more powerful! They use them for demonstrating quite a bit at the Ideal home etc. We find them good to fit in the odd little places in the car!
I've used the 'suitcase' type stoves and was not that impressed with them myself. Then again, I'm not that impressed with gas stobves that much anyway....
If I was going down that route I'd use a couple of single burner backpacking type stoves I think.
We love our Coleman twin burner petrol stove (and yes we are a family - 2 girls 8 and 4). Much more powerful burner (on ther main burner anyway) than the gas stoves I've tried, certainly than your typical 2 burner jobbie. You do need to carry petrol, but it's not as heavy as a gas bottle, and a petrol can is a nice easy to pack shape.
We feel it is perfectly safe in use. Many people seem to get the heeby-jeebies re petrol, but as long as you are sensible - which basically means refilling the tank (A once a day at the most job) outside, it is fine.
Have yet to find a gas stove I'd want to swap it for