we've just bought a croozer kid for 2 and we're really chuffed with it. it might be considered overkill for occasional trailer use but for the £400 it comes with a spinning buggy wheel and also a large wheel on extensions for use as a jogger and off road buggy.
it's very manouverable as a buggy, able to spin on its axis, and light. its good as a jogger, easy to steer with its weight pivoting easily on the back wheels, and good so fas as a trailer. we intend to use it full time as a double buggy with the baby sling we've also bought and with plenty of room for our (admittedly small) 3yr old. the boot is also huuuge!
its a bit wider (about 3") than a standard double buggy and you look a bit crazy down the co-op but if you can use it for more than just the trailer it starts to look reasonable value, especially when you consider only having to transport one bit of kid on hols etc. you can also trailer the kids to X, unhook the trailer and clip the buggy wheel in and push them the Y.
it's cheaper than the chariot but very well made, i think the difference is the lack of suspension, its also cheaper than the equivalent burley as it come with all the accesories.
hth