Don't hold me to it since I don't have files in front of me, however I think the discount is 10% - You can mount it on either side of the roll bars, I chose to mount mine on the inside - My straps do not show signs of stretching - I've not experienced yellowing or scratching on mine - I don't know about alternatives, I like mine so I've not shopped the market to see.
Hope that helps. if you have questions, I would suggest contacting Dr. Bob and speak with him directly. He sounds like as big a car nut as all of us! Try sending him a PM or an email if the phones are still acting up.