I put the 2015/4100 in my Beaver too. Use 2s l200 lipos, C gear, 10-8 gws prop. I like this setup.
I tied 3s and and it's way overpowered. Goes straight up though.
I wish the props didn't break so easy too. Would an apc be a little more durable?
A couple other guys have the 2015/3600 on B gear, 2s, and 10-8, and really like it. Goes about the same as my setup.