Steve, the SNII comes with the 50mm jaws standard and in truth you can do all the things you are talking about doing with just that one set of jaws. I used just the 50mm jaws for a long time while I was learning and did not realize I "needed" other jaws until someone showed me the advantages of different jaw sets.
However if you are going to start turning large bowl blanks, i.e. more than 4 inches thick I would recommend you go to the 75mm bowl jaw set which is thicker in cross section and designed specifically for the job. If you are going to turn outboard and start swinging 20 inch or larger platter blanks I would add the 130mm jaw set.
I would also recommend the 35mm spigot jaw set for gripping the ends of round sections that you would be turning for boxes or goblets. The spigot jaw set is a little longer in length and the inside of the jaws are serrated to give a tenacious grip on round stock that is only being held by the chuck. I love the spigot jaws for turning boxes as they really grab the end of a piece of wood and hold it so you can hog out the insides of an box blank in a hurry. Same technique applies for goblets.
If I were you I would only add the jaw sets as I determined I had a need for them. Of course if I had your money I would burn mine....:rolf:
I can hardly wait to hear your reviews of the DVR XP. What is really sweet about that machine is the fact that you can be experiencing vibration at one speed and you are able to just bump the RPM's up or down in 5 rpm increments until the vibration goes away. That is a real advantage on finishing cuts.