The two are very different beasts and you'll need to really evaluate what your needs are. If portability is a major concern than the NEX has a major advantage. It also has a better sensor. If flexibility is your main concern a DSLR will beat the NEX. Personally I have both a NEX and SLR and have found lately that unless i'm doing some serious work and need access to my better lenses the NEX gets 90% of the use. The form factor of a NEX means that I end up carrying it around at times where i'd have usually just left my camera at home before.