They look very interesting; I'm going to order some.
My two biggest doubts are the claim that the cavity back allows more powder to be loaded. Maybe so, but if a certain monolithic bullet weighs X amount, then the rear end is going to take up as much space no matter how its shaped, when seated to the same approximate overall length as similar spitzers.
Have also become a little leery of monos with very small hollow-points over the years, having seen more than one fail to open properly--the reason I much prefer plastic-tipped monos. (Large-caliber monos with big hollow points have always opened well.)
