I did not use a homemade pineapple syrup (just muddled a chunk of pineapple with some sugar and added a little bit of sugar syrup). Was good, with a nice pineapple hum, but not great. I did use a French Grape Brandy. Maybe a real Cognac may make it 5 stars.
As Mr Difford suggests you can ring the changes with different fruit syrups (and bitters). We thought it was delicious with passionfruit syrup instead of pineapple.
Just made this with what I had on hand - aged brandy, Grand Marnier, and basic simple syrup - and it's delicious. Possibly the tastiest cocktail with pineapple juice that I've had. Definitely making this again!