Like others, we wanted to dial down the sweetness a bit. We also wanted a bit more fruitiness. So we reduced the sugar syrup to 5ml, the fraise des bois (Merlet) to 25ml and instead of muddling the strawberries we juiced them and added 20ml. Lovely.
It was a bit sweet for my taste so I increased the rum to 2oz and added 1/2 oz. fresh lime juice. Kept everything else the same. Most friends liked this a bit better.
Wanted this a bit less sweet, so we cut back on the sugar syrup. Strawberries need to be very ripe and sweet. Works perfectly with a cold supper or at a brunch.