I think the idea of being able to edit your serato mixes more intuitively in live afterward is really cool.  Saving a mix tape is cool.  I don't know about having a limited live set inside serato though.  I feel like you just have to do one or the other.  Personally, i would just write tracks in live, then bounce them and play them whole in serato.  The change from vinyl to cd-j's then from cd-js to timecode vinyl/cds is already crazy.  This is too much for me to have to think about.  Ill stick to Live for now.  Its just so convenient.