The DF500 serves my needs 100%. For larger pieces, I've used it to build coffee and dining tables, a credenza and casework. Numerous hardwood cabinets, of course. Ladders, louver shutters, stools/steps, etc.
Chairs are on the drawing board (building isn't the hard part, coming with up a design that is elegant and robust has taken much longer than anticipated -- I have no desire of making plain chairs) and a double bed is also in the pipeline. No, you don't need a DF700 to build any of them, contrary to what someone might have told you. The trick lies in knowing when to design and use double or twin tenons.
I don't build or plan to build any full size-doors or outdoor tables for 12. If one day (very unlikely) I do need to build those, l'd use M&T -- by hand or with a router (don't want to buy another dowel drilling jig). If these two items are what you want or plan to do, get a DF700.
The best advice I'd give is to try out both at your local vendor, if possible. Handling it (make some test cuts if they allow you) to see how they feel to you (and then imagine doing that a hundred times -- 100 mortises milled in one single session is not a lot -- if you end up loving the machine as many do!).