Yes you can use sherry instead of white wine in shrimp scampi and it should turn out just fine.
I have used sherry in shrimp scampi before when I had run out of white wine and the shrimp scampi turned out just fine.
Although I do prefer to cook shrimp scampi with white wine the sherry did make the shrimp scampi turn out okay.
Sherry can work just as good in most recipes that call for white wine when cooking with it but if possible use sherry when the recipe calls for it and when the recipe calls for white whine use that also.
But sherry is a good substitute for white wine in Shrimp Scampi as well as many other recipes and foods that you cook with wine.