What keeps your heel in place is a good overall fit, rather than some peculiar shape of heel pocket. Sixth toe issues are often solved by footbed, or when too large for the footbed to solve the issue, grinding or stretchinng, but in any case the sixth toe should not affect your choice of boot. Go to a good bootfitter and get the boot which fits you best. All boots have some forward flex, and enough forward flex to ski well if the boot is fitted properly. I too am enthralled by the design of the Krypton/flexon, but with my gigantic calves this is never going to be the right boot for me, unless the bootmakers do something dramatically different with the cuff. The real questions to ask are how big are the boot's dimensions in areas that concern the typical skier. Forefoot width, instep height, heel width, cuff height, and cuff volume. Some boots have significant adjustablility in these dimensions. The bottom line is get the best bootfitter, and get the best liner, footbed and other services offered. The boot is merely a starting point, and in many cases many different model boots will serve you well.