I used to have an audio analysis/player programme that fingerprinted your collection (MusicIP) then you could create playlists by seeding the list with a chosen song and then apply characteristics to the resultant list the characteristics were radio like but also allowed to change the similarity, replace artists etc.
(http://musicip.wikia.com/wiki/Help_-_Basics)
I am not saying that this could be done in roon but some of the abilities that this gave is sort of replicated in the thumbs up and down in the radio pre-list. It would be good if in some non-resource constrained future a more complete radio function allowed more tweaking with
- play similar
- No repeat artist
- play more diverse
- play for 90 mins
etc options.
cheers
Ged