You can get a decent guitar solo out of biab soloists... However, you have to be willing to comp them... What does this mean? It means you have to generate 10 to 12 solos in biab... Just create a biab file for the number of measures for your solo... Then generate 12 versions of this...

Now export the solo to a sequencer... Let's assume the solo is 8 measures and they start at track 1 of your sequencer (cut out the count in)... Insert 12 tracks into your sequencer... Now, cut and paste each of the 8 measures into a separate track... So, in the end you wind up with 12 tracks each with a new occurrence of the 8 measure solo that you had in the long track that biab exported.

Now mute all except the first one... See what you like of that... The mute first and listen to the second one and see what you like of that... And so on for each track... By taking out the parts of the solo you don't like in each of the tracks, that makes a new part of the solo, you'll wind up with a good solo... this goes a lot quicker in practice than in actually explaining it... Anyway, It may be hard the first couple fo times, but after a while, get a good solo out of any instrument will come easy..