Hey, welcome back! :'D
I don't have much else to say than that this is great!
I always love to listen to collab pieces, as I find that some of the most interesting ideas are born from those :3
I think the way the guitar (and the drums) goes along with the orchestral instruments is amazing as well.
The loops is very smooth too.
I can definitely hear which ideas might've been who's XD
Mixing is pretty flawless.
Awesome job, both of you!