The chords that are there now will stay. Rhythm players are asked to add something to it. Whether you want to do so by adding 9th, 11th, 13th,6s etc is up to the person playing rhythm. In principal the notes you can use in your solo don't change. That a color tone is not in the chord you play over doesn't mean you can't play the color tone over it. If There's a combination of notes harmonically work as a chord you can also use those notes when you solo over the chord. Personally, I like to do this with fourths and sixths the most. John Mayer does it with seventhsI think what dominik is trying to say is some people KNOW what they want. Some people dont care where they go. And some know what they want but want to let others pick cause they can deal with either but would have a preference if given the choice. Everyone has their reasons for wanting a spot. Some people havent even touched the blues. Some spent the entire time there. It can be intimidating. So I see where he is coming from.
Just remember dominik that you are not going to use the solo for the collab. I think ids just confirmed that the backtrack actually wont be in the collab (I think that's what he said with bass and drums) and if that's the case its true those chords wont be used. You're rhythm could use 13ths over 5s or whatever. That changes the notes you can use slightly. So just go into it doing whatever. Dont think too hard.as you going in for a weakness.if you think you have one. Think of it like gonna blow it up in the blues and then do the metal for fun. Quite honestly the riff page is full of audition videos. I've seen you rock that penatonic scale and that's perfect for both blues and rock. You just gotta find the aminor position now for the solo.. or whatever scale you choose.