If you want to thin it out try to put down your discs on the ground like this (always thinking that you throw the disc the way you want to, leave your bad throws out): viewtopic.php?f=16&t=25664
Really helped me to put a few discs out and be able to put in some other ones that filles free spots which has definately improved my game.
When it comes to discs, I really have to say that I have fallen in love with MVP discs. Maybe if your friend has some of those, you might want to try an the Axis and Vector. I have two Axis' - one is pretty beat up for the 4 months I have it and has become slightly understable and my finesse disc when it comes to shots that I can't reach with a putter. I have one that has maybe hit 5 trees, and this one is laser straight on flat tunnel shots up to around 300', that's the furthest I can get with it. My vector is a really lovely disc for a headwind, it has no turn at all even thrown at full power and into a pretty heavy headwind. The only other other mid I have with me is a beat in ESP Meteor which turns about 60° for me so it makes my easy-to-make it-roll midrange.
Also, have you ever tried throwing spike hyzers with other discs than the Boss. That might work out too, so you could leave that one out of the bag.