I have one, mainly because nothing else would fit up my staircase. I picked up the bottom of the line bed, the 3000, then bought the foundation and legs on ebay. I've been using some foam on top of it and it works out pretty well. I need to pick up some better memory foam though. When you research the beds, you begin to realize that the only difference between them is the pieces of foam they include and the pillowtop. These are also the only things that will wear out. So I say get the cheapest one and add your own foam and/or pillowtop at your leisure. Its cheaper this way and will also be easily replaceable.
edit: to the OP, get the 7000 only if its cheaper than a new 3000. If its just cheap vs the retail price (i.e. still a grand or so), I'd avoid it.