A few more things I want to put out there:
1) The feature you are looking at (the 2-in-1 combos) are going to price you out of the other features you want, such as a larger SSD, or having any real processor speed. Just about all the convertable/detachable laptop/tablet combos I saw either had small SSDs (less than 100GB), or slower HDDs (5400rpm).
2) If you go the traditional laptop w/ touch screen support route, there are more options out there. Plus, you could also pick up a cheap laptop w/ a HDD, and simply purchase a SSD separately to replace your HDD. Going prices for 2.5" SSDs these days are around 2GB/$1, so a 500GB SSD would be close to $250ish.
3) If you want, you could always go the route of a small internal SSD, with a larger external HDD to store anything extra that won't fit. The biggest benefit of the SSD comes from having your OS installed on it, making the computer more responsive overall.