do you want speed or accuracy? a shorter brace height is usually fast but less forgiving. i think for anyone 300 is fast enough, people still kill people with recurves and they are no where near as fast. You are right with the z7, the arrow will be on the string for a longer time. it really depends what you have previously shot and what your preferences are. My youth bow had a 5" brace height, i'll tell ya that thing was very hard to group well past 20. Now i have a bear charge with a 7.5 inch brace height, and making that switch made all the difference in the world. If you have shot something with a brace height close to the z7 and you are hitting well, i think i would go for the extra fps.