I have tried, multiple times, to like a classic Negroni, but I just cannot. So my version of this attempt was Cayeya blanco tequila, Contratto Bitter, and Dolin Vermouth de Chambéry Blanc. Much better IMHO with the extra sweetness, perhaps sliding the scale down to a 5. (Where DOES one put the "blanc" modifier up there?)
Mine was Benchmark Old No. 8, Savory & James Amontillado, Amaro Nonino, Giacomo Sperone Vermouth di Torino. I picked something different for the Sherry, as Lustau Los Arcos didn't have great reviews.
Is a DRY Sherry the key?
Perhaps I hit a trifecta of mediocrity, but this didn't really do much for me.