you will get a small spark when connecting the batteries. at 6s it's not too big, but it will wear out your connector over time. Going to 8s/10s/12s you will see that spark really become larger.
Instead of a anti-spark switch (great but $$), i'd also look at a simple anti-spark loop key. Simple and easy, and cheap.
here's my how-to from a while back to make your own:
https://endless-sphere.com/forums/viewtopic.php?f=35&t=72687&hilit=loop+key
GL!