Have a Drifta pull out myself and have found the following;
Large bench /cupboard space. Usefull with youngster. Will obviously depend greatly on what you need.
Does take up considerable room within the trailer. Used with a drifta storage unit, what remaining space you do have can be used efficiently.
A tailgate version will require sturdy hinges on the trailer or else, over time they will sag and you'll find yourself lifting the tailgate into place when shutting.
We have the DPOR (I think from memory) and takes no time and little effort to extract and put away.
Anything Drifta is frightfully $$$, but you will be assured of the absolute best quality.
If it's going into a trailer with a chequerplate floor, there is a simple and cost effective mod (which I had to do) that stops the poly runners being torn away by the rough finish of the chequerplate (see Drifta website's FAQ page, they posted the solution I came up with and submitted to them).
If your looking at the occasional weekend away, the tailgate version may just be the best bet (considerably cheaper), but if you are looking at longer stays, a bit more creature comfort, and especially helpful with kids I would suggest the extra $$ is well spent, my wife is a convert from hating camping to being happy to go now she has a fully equiped kitchen in tow
If your still wondering, do yourelf a favour and call Luke from Drifta, he's a top bloke who can't bend over backwards enough to please.