Your method seems to work indeed.. problems I encountered: (i)it goes extremely slow using the app on my imac, (ii)it would be so much easier if spotify would just import the existing itunes playlists and (iii)my playlist contained more than 1000 songs, when trying to use it as the basis of a 'radio', it didn't work.. I don't seem to find an easy way to create a radio which is a bit varied - all radios are one-dimensional, per artist or genre and I just like mixing..
The only issue with this is that as soon as I delete that folder, Spotify can no longer locate the songs. I don't want to have to store duplicates of all my music. Really wish they hadn't gotten rid of this feature.
Thank you for this - first solution I've found to actually work on importing playlists into Spotify. Even the built in integration Spotify previously had never worked correctly, nor did any of the web based conversion solutions I've tried to convert / replicate a local library in Spotify.