I’ve actually owned both vises. I liked the spartan. But love the Peak vise. As far as hook sizes for the peak – I have the standard jaw (not the midge) and I tie mainly trout flies #8 to #22 and I have yet to have a hook slip. I’m not really into rotary tying but it does come in really handy being able to turn the fly over.
Why do I like it better than the spartan? For me the spartan was difficult to get larger trout sized hooks locked in – it took a lot of force to get it locked down for size #8 and #10 hooks and even then the hook would sometimes slip. The peak also has a “positive stop” on the cam which I also prefer.
The spartan is a very nice vise – one of the best. But the Peak just works better for me.
Greg