banana and walnut muffins

for jacqs. wednesday's creation while hanging in newy.

i tweaked her recipe for yummy fruit and nut goodness. always looking out for ways to add extra nutrients and variety to my meals and snacks.

ingredients
2cups SR flour
1/2 cup wholemeal SR flour
1/2 tsp bicarb soda
1/2 tsp nutmeg
1/2 cup brown sugar
1/2 cup crushed walnts (extra walnuts for finishing touch if desired)
1 1/4 cup milk
1 tsp vanilla
4 ripe bananas mashed
100g butter melted & cooled

method
pre-heat oven to 200degC.
lightly brush 12cup muffin tray holes with oil or melted butter/place out muffin cases.
sift flours, bicarb & nutmeg into a large bowl, then add husks from the flour.
stir in the sugar and walnuts. make a well in the centre.
in a jug whisk together eggs, milk and vanilla, pour into well.
add the banana and butter.
fold gently with a metal spoon until just combined. don't over mix.
fill each muffin hole 3/4 full with mixture.
back for 20-25mins or until muffins rise, golden and come away slightly from the tin.

QUESTION: what advanted does using a metal spoon give? any answers from seasoned cooks out there?