I committed to making this today following a request for a 'something different' drink. I knew my version would involve improvisations but I wasn't expecting to have use guava juice in lieu of pineapple! Nevertheless I pressed on: (all in mls) 50 Edinburgh Gin, 20 Wild Kirsch, 10 Cointreau, 2.5 Becherovka, 15 lime juice, 2.5 agave syrup, 60 guava. Surprisingly good, perhaps more Pratapgarh, than Singapore, Sling, but I'd do it again!