I used the mount with a backward pull yesterday with just a bit of a hard initial tug, but it was much better than having to pull forward toward the shifters. I noticed during the ride I was feeling a slight irritation on my arms touching some sharp edges on the computer mount ring.

Post ride when I got home I worked on the inside of the computer mount ring using a dremel with a very fine sanding bit then used a 220 grit sand paper to smooth it out the dremel work and then a 1000 grit wet sand paper with chain oil. I only sanded the upper portion of the computer ring since the bottle cage is on the lower portion. I also took off the slight sharp outer edges from production molding. The ultra fine sand paper was just to make the appearance better even though the ring is not easily picked up by eye.

I still need to give a road test, but post sanding the Specialized Purist bottle seems to be working like a charm or nearly.......

Well at least I will give a try for a while longer and I will try the forward pull again.

Edit: please note that I did not remove much material from the inside of the computer mount ring. I believe that the designer made it tight so as to eliminate vibration of the computer and give stability to the display. I know that some of my homemade mounts a few years ago had enough vibration that I couldn't read the numbers on rougher pavement. :-)