Well, I found the tip was a little unevely profiled in the thin axis, and rolled off the string because of a too-steep taper to begin with, it was sort of a little half-diamond profiled if you look down the point, so I flattened it. Most of your pictures dont show the same sort of thing.
Also, the curve of it created an odd angle whereby in downstrokes it hit the string a little shallow and in upstokes it hit hooked the string a tad, so when I leveled out the profile of the tip I did it asymmetrically so that the pick hit flat.
Minor things really, just being fussy. Most of your pics dont seem to have a pretty flat, level profile at the tip, so perhaps its just something to be mindfull of when making the curved/shell grip ones?
It certainly can take aggressive playing. I have a riff in one of my tracks thats fast, hard-picked alternate double stops and chords, and its really quite difficult: it requires a lot of force, driving through powerchords at ~260bpm and most picks sort of jam on the strings and the flow breaks, but between the nature of the material and how it interacts with the string (mostly slides through quite easily, but with a nice amount of grip) and the mechanical properties of it, its energy-impartment to the string because its stiff, I was able to play the riff much more easily than usual, and the pick suffered no harm (a recording of this riff can be heard in my track 'holy tyranny' on players - its what might pass for the chorus, and its too slow on there: I had trouble 4-tracking it at its correct speed, so its reduced to 245bpm).
I'll be sending the paypal for a couple more today.