HMH jaws are hardened tool steel, and they are guaranteed to last a lifetime. The shape and profile are carefully designed so that you can put enough steel on a hook to hold it well, BUT also so that you can actually get to the hook with your fingers so you can position materials. Access to the hook is the most important thing in fly tying, and no other premium vise manufacturer out there can give you the unencumbered access to hooks that you get with all HMH vises and jaws.
All-around jaws are a fine idea, and our Omni jaw is brilliant at a wide range of hooks. But if you're serious about working on extreme hook sizes, say, #20s and smaller, or above 2/0, then you should consider the vise that gives you the jaw that's best for the job.