As already noted the tip shape is not of major importance. But there is a difference though, the flat upswept bottom effectively increases the dihedral effect at low speed. So if you are using the higher dihedral no aileron wing the then you will never know the differance over a blunted or rounded tip.

If you have flatened the wing or had very low dihedral wing such as in the Nitro planes Super Senior then this small reduction in dihedral effect will be noticible not neccessarily bad but noticible.

John