Will the Banana Magic be better for hitting kickers/Jibs than my NS Legacy?
No. The Magic is way stiffer than the Legacy and has considerably more rocker in the profile. As a result it floats better in powder (despite being a pure twin as opposed to the directional Legacy) and is great for turning/slashing. But while it holds an edge really well (the Magnetraction is possibly the most aggressive of all Mervin boards) it does tend to be squirrelly on hardpack and groomers.
Frankly, you are much better off with the Legacy for most thinks park related.