For our 2017 Brewola we made a Biere de Garde using Briess Copper Malt as a featured ingredient. The recipe, available here, used a basic Belgian Pilsner base with some dark Munich malt, and an equal amount of Copper Malt. The beers were made at various times, starting in November through mid-February. Thanks to the broad nature of the Biere de Garde style our brewers were able to use a wide variety of yeast, ranging from Kolsch yeasts to saison yeasts to Scottish yeasts.
The general consensus on the beers was that they were good, with no particular combination of yeast and process causing one to stand out amongst the rest. This led us to conclude that the recipe and Copper Malt, in particular, were both solid. We used a high percentage of Copper Malt in the grist and ultimately would probably recommend using less, though flavour profile of Copper Malt is quite pleasant at the level we used. You can read more in depth about the results from the tasting here.